The viscosity and shear thinning behavior are essential characteristics of tomato ketchup. A real-time monitoring of those characteristics during processing is important to obtain a good quality of the final product and to reduce production waste. This work investigates the measurement of rheological in-line flow properties of tomato ketchup, using a real-time technique that combines ultrasound velocity profiling (UVP) and pressure difference (PD) assessment. In-line data were compared to those obtained off-line using a rotational viscometer. There was a poor correlation with the Bostwick measurement, whereas the flow curves calculated from flow velocimetry data were very similar to those measured off-line. The extensional viscosity of ketchup was determined through the measurement of Hyperbolic Contraction Flow; the curve followed a trend similar to that for the shear viscosity over the deformation rate investigated.

The ultrasound velocity profiling technique (UVP) was used to study flow structures after a two-dimensional (2-D) 1:11 sudden expansion of pulp fiber suspensions at varied average velocities (1-2.2 m/s) and concentrations (1.8 and 2.8 wt %). One advantage of studying jet geometry is the potential to investigate the main flow structures away from walls. Measurements done at the same percent of the total jet length, at constant concentration, show that an increase in flow rate gave a faster decrease in centerline velocity and a quicker increase in jet width. Increasing the concentration, at the same jet length, the centerline velocity was more stable and the width of the mixing layer increased more rapidly. Comparisons with CFD simulations in the laminar regime, using the Bingham plastic model, show that the main flow structures were captured if the yield stress used in the simulations is approximately 20% of the measured using a rheometer.

An Ultrasound Velocity profiling (UVP) technique is used in this study to investigate the pipe flow of pulp suspensions in the near wall region. Four flow rates and two consistencies were investigated: 1.9 and 4.8% (w/w) consistency. The mean velocity profiles showed a distinct plug at the centre of the pipe, surrounded by a sharp velocity gradient. The plug size increased with increasing consistency or decreasing bulk velocity. The demodulated echo amplitude (DMEA) profile slowly rises from low values near the wall to a distinct maximum at the plug front before slowly decaying towards the pipe centre. Since only the fibres and fines contribute to the attenuation of ultrasound, the demodulated echo amplitude profiles thus indicate and support the hypothesis of the existence of a consistency profile in the near wall area, with a decreasing amount of fines and fibres close to the pipe wall.

Because of many advantages of ultrasonic velocity profile (UVP) -measurement, the range of industrial applications is very wide. In this chapter, flowrate measurement, food and suspension flow, and measurement around a ship are introduced as examples of applications for UVP measurement in the industrial field. In the fields of flowrate measurement, studies concerning with the accuracy of this flowrate measurement method and calibration results of an actual flow are described, including application examples such as open channel and multi-line measurement. In the field of food and suspension flow, taking advantage of its applicability to opaque fluid, a velocity measurement is performed for fluid such as tomato soup and chocolate. Using the in-line UVP + PD method, measurements of transient flow such as thermal processing and liquid displacement, which are very important in the food industry, are performed. Measurement around a ship is an application example taking advantage of the compact installation possible for an ultrasonic sensor. Ultrasonic transducers are installed on the bottom of the actual ship, and measurement examples of velocity profile and Reynolds stress are introduced.

Measurements of the viscosity of non-Newtonian fluids and suspensions having a solid volume fraction of about 30% or more is of major interest from an industrial point of view. Cement paste and cement grouts for injection grouting applications, with water to cement ratios typically in the range of 0.4 and 0.6 - 0.8 by weight, are two examples of industrial fluid systems. Few in-line techniques are available on the market that can be used for these fluid systems and under realistic field conditions. The so-called UVP+PD in-line rheometry method combining the Ultrasound Velocity Profiling (UVP) technique with Pressure Difference (PD) measurements is a promising new tool for industrial applications. This paper presents an initial pre-study that aims to demonstrate the feasibility of the UVP+PD method using cement grouts for process monitoring and control of grouting applications under realistic field conditions. The UVP+PD method was tested and found successful for continuous inline measurements of concentrated micro cement-based grouts with water/cement ratios of 0.6 and 0.8. The test set-up consisted of a combination of an experimental " flow loop" and a conventional field grouting rig - UNIGROUT, from Atlas Copco. The rheological properties were determined, directly in-line and the parameters obtained were subsequently compared with off-line measurements using a conventional rotational rheometer.

In construction, grouting is used to improve or alter the natural properties of soil or rock by injecting a grout into the pores or fractures of the formation. In order to predict the grout penetration progress and maximum penetration length, modern methods for grouting design involve a detailed knowledge of the rheological properties of the used grout. Today, rheological properties of grouts are measured either in a laboratory with conventional rheometers or in the field with simple devices. Due to the complex flow behavior of cement-based grouts, being non-Newtonian yield stress fluids with history and time dependent rheological properties, the results are non-consistent, device dependent and strongly influenced by the test procedure and operator. No standard measurement method is available for rheological characterization of grouts in the grouting industry today. In order to improve this unfortunate situation a new complete measuring methodology, based on pulsed ultrasound, is proposed. The method has been tested for cement-based grouts, with good results. In this work, a new container-based field laboratory is presented, equipped with the Flow-Viz system, which is designed for in-line measurements of rheological properties of cement-based grouts under field-like conditions. Results obtained under field-like conditions are presented in order to demonstrate the applicability of the new system.

In this project a non-Newtonian CMC model fluid was tested in two different complex geometries using Ultrasonic Velocity Profiling (UVP). Velocity profiles were measured at three different positions at the center (contraction) of a specially manufactured 50% open diaphragm valve. The complex geometry coordinates and velocity magnitudes were analysed and compared to the bulk flow rate measured using an electromagnetic flow meter. The difference between the calculated and measured flow rates varied from 15% to 25%. A complete flow map in the axial direction from developed to contracting flow was also measured by scanning the transducer along a hyperbolic contraction using a high precision robotic arm set-up. Experimental results obtained using UVP showed good agreement (10%) with theoretical predictions. Results showed that it was possible, for the first time, to measure quantitative velocity data for non-Newtonian flow in a complex geometry, such as a diaphragm valve. It was found that the most important problem in order to increase measurement accuracy is the estimation of wall interface positions, which is due to the ultrasonic transducer's near field. This problem can be eliminated by the introduction of a next generation transducer, which is currently under development. © 2010 Elsevier Ltd.

In this project, velocity profiles were measured in a diaphragm valve using an ultrasonic velocity profiling (UVP) technique. A non-Newtonian CMC model fluid was tested in this highly complex geometry and velocity profiles were measured at four different positions at the centre (contraction) of a specially manufactured 50% open diaphragm valve. The coordinates of the complex geometry and velocity magnitudes were analysed and compared to the bulk flow rate measured using an electromagnetic flow meter. Two different ultrasonic transducers (standard and delay line) were used and results were compared in order to assess velocity data close to wall interfaces as well as the accuracy and magnitude of measured velocities. The difference between calculated and measured flow rates was 32% when using the standard ultrasonic transducers. The error difference decreased to 18% when delay line transducers were introduced to the measurements. The velocity data obtained in the diaphragm valve showed a significant improvement close to the wall interfaces when using the delay line transducers. The main limitation when using delay line transducers is that beam refraction can significantly complicate measurements in a highly complex geometry such as a diaphragm valve. A new delay line transducer with no beam refraction could provide a solution. The introduction of delay line transducers showed that UVP can be used as a powerful tool for detailed flow behaviour measurements in complex geometries.

Ultrasonic velocity profiling (UVP) is a technique that can measure an instantaneous one-dimensional velocity profile in a fluid containing particles across the ultrasonic beam axis or measurement line. A methodology for in-line rheometry combining the UVP technique with pressure difference (PD) measurements, commonly known as UVP+PD, has been developed and improved at the Swedish Institute for Food and Biotechnology and the Cape Peninsula University of Technology (Wiklund, (1); Wiklund et al., (2); Kotzć et al., (3)). The UVP+PD methodology allows measurements that are not possible with common rheometers such as radial velocity profiles and yield stress directly in-line and under true dynamic process conditions. Furthermore, it has advantages over commercially available process rheometers and off-line instruments in being noninvasive, applicable to opaque and concentrated suspensions and having small sensor dimensions. It has been evaluated for several potential industrial applications including, for example, paper pulp, foods, transient flows and model mineral suspensions. Similarly, the UVP technique can be applied to open channel flow by combining flow depth measurements in order to obtain rheological properties in-line. Industrial fluids, such as thickened paste etc., commonly found in tailings transportation exhibit wide particle size distributions, large particle sizes and very high viscosities. These industrial fluids cause strong attenuation of the ultrasound energy, which can significantly distort velocity profiles measured with the UVP technique or even make it impossible to conduct flow measurements at all with optical techniques. Initial results obtained in concentrated cement pastes and grouts as well as bentonite showed that UVP is a feasible and promising technique for flow visualisation and rheological characterisation in complex fluids. The results obtained showed significant potential for application in more viscous fluids and larger pipe diameters using new transducers and acoustic coupling technologies.

Pulsed Ultrasonic Velocimetry, commonly referred to as Ultrasonic Velocity Profiling (UVP) in research and engineering applications, is both a method and a device to measure an instantaneous one-dimensional velocity profile in opaque fluids along a measurement axis by using Doppler echography. Studies have suggested that the accuracy of the measured velocity gradient close to wall interfaces need to be improved. The reason for this is due to distortion caused by cavities situated in front of ultrasonic transducers, measurement volumes overlapping wall interfaces, refraction of the ultrasonic wave as well as sound velocity variations (Doppler angle changes). In order to increase the accuracy of velocity data close to wall interfaces and solve previous problems a specially designed delay line transducer was acoustically characterised and evaluated. Velocity profiles measured using the delay line transducer, were initially distorted due to the effect of finite sample volume characteristics and propagation through the delay line material boundary layers. These negative effects were overcome by measuring physical properties of the ultrasonic beam and implementing a newly developed deconvolution procedure. Furthermore, custom velocity estimation algorithms were developed, which improved the time resolution and penetration depth of the UVP system. The optimised UVP system was evaluated and compared to standard transducers in three different straight pipes (inner diameters of 16, 22.5 and 52.8 mm). Velocity data obtained using the optimised UVP system showed significant improvement close to wall interfaces where the velocity gradients are high. The new transducer technology and signal processing techniques reduced previously mentioned problems and are now more suitable for industrial process monitoring and control.

Ultrasonic Velocity Profiling (UVP) is a powerful technique for velocity profile measurements in research and engineering applications as it is the only available method that is cost-effective, relatively easy to implement and applicable to opaque fluid suspensions, which are frequently found in industry. UVP can also be combined with Pressure Drop (PD) measurements in order to obtain rheological parameters of non-Newtonian fluids by fitting theoretical rheological models to a single velocity profile measurement. The flow properties of complex fluids are almost exclusively obtained today using commercially available instruments, such as conventional rotational rheometers or tube (capillary) viscometers. Since these methods are time-consuming and unsuitable for real-time process monitoring, the UVP+PD methodology becomes a very attractive alternative for in-line flow behavior monitoring as well as quality control in industrial applications. However, the accuracy of the UVP+PD methodology is highly dependent on the shape and magnitude of the measured velocity profiles and there are still a few problems remaining with current instrumentation and methods in order to achieve the robustness and accuracy required in industrial applications. The main objective of this research work was to optimize an UVP+PD system by implementing new transducer technology and signal processing techniques for more accurate velocity profile measurements as well as rheological characterization of complex fluids under industrial/realistic conditions. The new methodology was evaluated in two different pipe diameters (22.5 and 52.8mm) and tested with three different non-Newtonian fluids in order to obtain a wide range of rheological parameters. Results were also compared to conventional rotational rheometry and tube viscometry. It was found that rheological parameters obtained from accurate velocity data across the pipe radius, especially close to pipe walls where the velocity gradient is high, showed better agreement to conventional rheometry than when compared to results obtained using profiles measured with conventional UVP instrumentation and commercial software (Met-Flow SA Version 3.0). The UVP+PD method is now more robust and accurate. The main challenge remaining is to successfully implement a complete non-invasive system in industrial processes that is able to achieve real-time and accurate complex flow monitoring of non-Newtonian fluid suspensions.

Industrial applications involving pulsed ultrasound instrumentation require complete non-invasive setups due to high temperatures, pressures and possible abrasive fluids. Recently, new pulser-receiver electronics and a new sensor unit were developed by Flow-Viz. The complete sensor unit setup enables non-invasive Doppler measurements through high grade stainless steel. In this work a non-invasive sensor unit developed for one inch pipes (22.5 mm ID) and two inch pipes (48.4 mm ID) were evaluated. Performance tests were conducted using a Doppler string phantom setup and the Doppler velocity results were compared to the moving string target velocities. Eight different positions along the pipe internal diameter (22.5 mm) were investigated and at each position six speeds (0.1-0.6 m/s) were tested. Error differences ranged from 0.18 to 7.8% for the tested velocity range. The average accuracy of Doppler measurements for the 22.5 mm sensor unit decreased slightly from 1.3 to 2.3% across the ultrasound beam axis. Eleven positions were tested along the diameter of the 48.4 mm pipe (eight positions covered the pipe radius) and five speeds were tested (0.2-0.6 m/s). The average accuracy of Doppler measurements for the 48.4 mm sensor unit was between 2.4 and 5.9%, with the lowest accuracy at the point furthest away from the sensor unit. Error differences varied between 0.07 and 11.85% for the tested velocity range, where mostly overestimated velocities were recorded. This systematic error explains the higher average error difference percentage when comparing the 48.4 mm (2.4-5.9%) and 22.5 mm (1.3-2.3%) sensor unit performance. The overall performance of the combined Flow-Viz system (electronics, software, sensor) was excellent as similar or higher errors were typically reported in the medical field. This study has for the first time validated non-invasive Doppler measurements through high grade stainless steel pipes by using an advanced string phantom setup.

Ultrasonic velocity profiling (UVP) is a technique that can measure an instantaneous one-dimensional velocity profile in a fluid containing particles across the ultrasonic beam axis or measurement line. A method for in-line rheometry combining the UVP technique with pressure difference (PD) measurements (UVP+PD), was developed and improved at SP - Technical Research Institute of Sweden and the Cape Peninsula University of Technology, South Africa. The UVP+PD methodology allows measurements that are not possible with common rheometers such as radial velocity profiles and yield stress directly in-line and under true dynamic process conditions. Furthermore, it has advantages over commercially available process rheometers and offline instruments in being non-invasive, applicable to opaque and concentrated suspensions, and having small sensor dimensions. It has been evaluated for several potential industrial applications including paper pulp, foods, transient flows, and model mineral suspensions. Similarly, the UVP technique can be applied to an open-channel flow by combining flow depth measurements to obtain rheological properties in-line. Industrial fluids, such as thickened pastes, commonly found in tailings transportation exhibit wide particle size distributions, large particle sizes, and very high viscosities. These industrial fluids cause strong attenuation of the ultrasound energy, which can significantly distort velocity profiles measured with the UVP technique or even make it impossible to conduct flow measurements. Initial results obtained in concentrated cement pastes and grouts (bentonite and kaolin clay) showed that UVP is a feasible and promising technique for flow characterization in viscous fluids.

The characterization of fluids flowing in industrial pipes is of paramount importance to optimize the production process and guarantee the final product quality in most industries. Rheological parameters of the fluid can be efficiently calculated starting from the Pressure Drop (PD) along a tract of the pipe, and the velocity profile that the flow develops along the pipe diameter, which can be assessed through Ultrasounds Pulsed Wave Doppler (PWD). Unfortunately, in PWD the maximum detectable velocity is restricted by the aliasing limit related to the Pulse Repetition Frequency (PRF). The use of PRF sequences at different rate can recover de-aliased velocities by combining the aliased data. In this work, we extend the capabilities of an embedded PWD ultrasound system used to characterize industrial fluids by implementing, in real-time, the multi-PRF method.

The continuous monitoring of rheological parameters of industrial fluids during production is of paramount importance for process and quality control. Up to now, no system capable of a complete and non-invasive in-line measurement is commercially available, so that only time discrete laboratory measurements on fluids specimens are possible. In this work a new, fully integrated ultrasound system for in-line fluid characterization, named Flow-Viz, is presented. The system measures the velocity profile of the fluid moving in a pipe through pulsed Doppler ultrasound, and combines it with the pressure drop. The electronics, featuring two ultrasound transmission/reception channels used alone or in pitch-catch configuration, includes powerful digital processing capabilities for real-time velocity profile calculation, and is fully programmable. Particular attention is paid to low-noise design for achieving the optimal performance in highly attenuating suspensions. An application is presented where the system, coupled to a non-invasive ultrasound sensor unit, performs in-line rheological measurements through the wall of a high-grade stainless steel pipe.

People who suffer from swallowing disorders, commonly referred to as dysphagia, are often restricted to a texture-modified diet. In such a diet, the texture of the fluid is modified mainly by the addition of gum or starch-based thickeners. For optimal modification of the texture, tunable rheological parameters are shear viscosity, yield stress, and elasticity. In this work, the flow properties of commercial thickeners obtained from major commercial suppliers were measured both in shear and extensional flow using a laboratory viscometer and a newly developed tube viscometry technique, termed Pulsed Ultrasound Velocimetry plus Pressure Drop (PUV+PD). The two methods gave similar results, demonstrating that the PUV+PD technique can be applied to study flow during the swallowing process in geometry similar to that of the swallowing tract. The thickeners were characterized in relation to extensional viscosity using the Hyperbolic Contraction Flow (HCF) method, with microscopy used as a complementary method for visualization of the fluid structure. The gum-based thickeners had significantly higher extensional viscosities than the starch-based thickeners. The rheological behavior was manifested in the microstructure as a hydrocolloid network with dimensions in the nanometer range for the gum-based thickeners. The starch-based thickeners displayed a granular structure in the micrometer range. In addition, the commercial thickeners were compared to model fluids (Boger, Newtonian and Shear-thinning) set to equal shear viscosity at 50s−1 and it was demonstrated that their rheological behavior could be tuned between highly elastic, extension-thickening to Newtonian. This article is protected by copyright. All rights reserved.

The Ultrasound Velocity Profiling (UVP) technique allows real-time, non-invasive flow mapping of a fluid along a 1D-measuring line. This study explores the possibility of using the UVP technique and X-ray video-fluoroscopy (XVF) to elucidate the deglutition process with the focus on bolus rheology. By positioning the UVP probe so that the pulsed ultrasonic beam passes behind the air-filled trachea, the bolus flow in the pharynx can be measured. Healthy subjects in a clinical study swallowed fluids with different rheological properties: Newtonian (constant shear viscosity and non-elastic); Boger (constant shear viscosity and elastic); and shear thinning (shear rate-dependent shear viscosity and elastic). The results from both the UVP and XVF reveal higher velocities for the shear thinning fluid, followed by the Boger and the Newtonian fluids, demonstrating that the UVP method has equivalent sensitivities for detecting the velocities of fluids with different rheological properties. The velocity of the contraction wave that clears the pharynx was measured in the UVP and found to be independent of bolus rheology. The results show that UVP not only assesses accurately the fluid velocity in a bolus flow, but it can also monitor the structural changes that take place in response to a bolus flow, with the added advantage of being a completely non-invasive technique that does not require the introduction of contrast media. © 2020, The Author(s).

Human swallowing taking place in the pharynx is a complex process demanding precise co-ordination amongst the organs involved. People suffering from swallowing disorders are restricted to texture altered foods/drinks which are shear thinning necessitating the knowledge of shear deformation during pharyngeal transport. In this work, the shear rate during bolus transport using shear thinning boluses was measured and reported both during in-vivo and in-vitro experiments.

Dysphagia refers to difficulties in swallowing, caused by conditions ranging from trauma to neurological disorders such as dementia. People suffering from dysphagia cannot adequately transfer food from the mouth to the stomach especially low viscosity, fluid foods. Texture modification is imperative to ensure safe passage of food from mouth into the stomach. Food products with elastic properties, i.e. high extensional viscosity, have been identified as helpful in promoting safe swallowing. However, this hypothesis is difficult to prove by clinical studies due to ethical issues and availability of suitable patients. Moreover, the problems of individual patients vary largely in nature and extent which further complicates the matter as identified in our previous research (1). We are currently constructing an in vitro human swallowing apparatus mimicking swallowing through the pharynx to the esophagus. The apparatus will have the pressure and ultrasound sensors to monitor real time flow properties of the bolus as it travels along the swallowing tract. This will enable us to measure relevant parameters during swallowing such as residence times and bolus velocity along the way. The model can be adjusted to different dysphagic conditions such as abnormal epiglottis closure. The goal of the project is to develop food products for safe swallowing and currently we are determining the rheological properties of commercial dysphagia thickeners, as well as model fluids. Two companies active in dysphagia foods are contributing (Fresenius Kabi and Findus). The shear and extensional properties have been shown to vary significantly, which has been correlated with fluid microstructure.

The rheological properties of cement based grouts change with water/cement ratio and time, during the course of hydration. For this reason, it is desirable to be able to measure this change continuously, in-line, with a robust instrument during the entire grouting operation in the field.The rheological properties of commonly used cement grouts were determined using the Ultrasound Velocity Profiling combined with the Pressure Difference (UVP. +. PD) method. A non-model approach was used that directly provides the properties, and the results were compared with the properties obtained using the Bingham and Herschel-Bulkley rheological models. The results show that it is possible to determine the rheological properties, as well as variations with concentration and time, with this method.The UVP. +. PD method has been found to be an effective measuring device for velocity profile visualization, volumetric flow determination and the characteristics of the grout pump used.

The rheology of cement grout is complex due to its thixotropic nature and the presence of a yield stress. Despite the importance of the yield stress for grouting design, no standard methods are yet available to determine the yield stress. Most common methods are based on using conventional rheometers, but the results are subjective due to the measurement techniques, applied shear history and hydration. In this work, measurement of the yield stress of cement grout was performed with different measurement techniques using a conventional rheometer. In addition, in-line measurements using an ultrasound based technique were made in order to visualize the flow profile and perform a direct measurement of the yield stress. Two ranges of yield stress, static and dynamic yield stress, were measured. These results should be used for design purposes depending on the prevailing shear rate. The ultrasound based Flow Viz industrial rheometer was found capable of performing direct in-line measurement of the yield stress and providing a detailed visualization of the velocity profile of cement grout.

A numerical scheme based on the volume of fluid (VOF) method for predicting the displacement of one liquid by another has been verified versus electrical resistance tomography (ERT) and ultrasonic velocity profile (UVP) measurements for the displacement of yoghurt by water. The scheme using the VOF method predicts the skewed phase distribution as measured using ERT and the global structure of the velocity profile as measured using UVP. The phase distribution using the VOF method was compared with the results using the species transport model which allows for mixing between the phases. The species transport model was found to be less suitable for predicting the displacement of yoghurt by water since the turbulence model was unable to accurately predict the turbulent viscosity in the mixing zone between yoghurt and water, which resulted in a too high rate of mixing. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The in-line assessment of the rheological properties of fluids in chemical, cosmetic, pharmaceutical, and food industries is fundamental for process optimization and product quality. The rheology of a fluid in a process pipe can be investigated by combining the measured pressure difference over a fixed distance of pipe, and the velocity distribution of the fluid along the diameter. The latter data can be measured by Pulsed Ultrasound Velocimetry (PUV), which is a non-invasive Doppler technique. Till now, the few systems available need cumbersome electronics or computer for data post-processing and are not suitable for industrial applications. In this work we present a compact (10 × 12 cm), fully programmable and low cost system that embeds the ultrasound front-end and all of the digital electronics necessary for the signal processing. The board produces, in real time, 512-point velocity profiles at 45 Hz rate and is integrated in the Flow-VizTM platform (SP Technical Research Institute of Sweden).

The rheology of a fluid flowing in an industrial process pipe can be calculated by combining the pressure drop and the velocity profile that the fluid develops across the tube diameter. The profile is obtained noninvasively through an ultrasound Doppler investigation. Unfortunately, at present, no system capable of real-time velocity profile assessment is available for in-line industrial rheological measurements, and tests are operated by manually moving fluid specimens to specialized laboratories. In this work, we present an embedded system capable of in-line and real-time measurement of velocity profile and pressure drop, which enables the automatic rheological characterization of non-Newtonian fluids in process pipes. The system includes all the electronics for the ultrasound front-end, as well as the digital devices for the real-time calculation of the velocity profile. The proposed system is highly programmable, low-noise, and specifically targeted for industrial use. It is shown capable of producing, for example, 512-point velocity profiles at 45 Hz rate. An application is presented where a sludge fluid, flowing at 600 L/min in a 48 mm diameter high-grade stainless steel pipe, is characterized in real-time with a ±5% accuracy.

Modern industries need to monitor every step of the production process for a better efficiency and product quality. However, important parameters, like the rheological indexes of the fluids involved in the process, cannot easily be inspected inline, as they are typically analyzed through off-line laboratory tests on specimens. Recently, electronics sensors have been introduced capable to characterize in-line the fluids by acquiring the velocity profile of the fluid flowing in a pipe, and the pressure drop. These sensors are based on Pulsed Wave Doppler (PWD), where ultrasound energy bursts are transmitted at Pulse Repetition Frequency (PRF) rate. The fluid maximum velocity that can be safely investigated in PWD is constrained by the PRF, which is limited by the investigation depth. Unfortunately, in large industrial pipes, the fluid velocity can be easily beyond the Nyquist limit, preventing a correct ultrasound investigation. Staggered PRF is a technique typically used in Doppler radar that, by exploiting PRF sequences at different rate, can recover the right velocity even if beyond the Nyquist limit. In this work, an embedded ultrasound system for in-line rheological investigation is updated by implementing in its Field Programmable Gate Array (FPGA) the staggered PRF technique. Experiments show the system capable of detecting velocity profiles at 25 Hz rate beyond the Nyquist limit.

The newly developed Flow-Viz rheometric system is capable of performing detailed non-invasive velocimetry measurements through industrial stainless steel pipes. However, in order to improve the current design for non-invasive measurements in industrial fluids, pulsed ultrasound sensors need to be acoustically characterized. In this paper, acoustic characterization tests were carried out, with the aim of measuring the ultrasound beam propagation through stainless steel (SS316L) pipes and into water. For these tests, a high-precision robotic XYZ-scanner and needle hydrophone setup was used. Several ultrasound sensor configurations were mounted onto stainless steel pipes, while using different coupling media between the transducer-to-wedge and sensor wedge-to-pipe boundaries. The ultrasound beam propagation after the wall interface was measured by using a planar measuring technique along the beam's focal axis. By using this technique, the output for each test was a 2-D acoustic color map detailing the acoustic intensity of the ultrasound beam. Measured beam properties depicted critical parameters, such as the start distance of the focal zone, focal zone length, Doppler angle, and peak energy within the focal zone. Variations in the measured beam properties were highly dependent on the acoustic couplants used at the different interfaces within the sensor unit. Complete non-invasive Doppler ultrasound sensor technology was for the first time acoustically characterized through industrial grade stainless steel. This information will now be used to further optimize the non-invasive technology for advanced industrial applications.

The pharynx is critical for correct swallowing, facilitating the transport of both air and food transport in a highly coordinated manner, and aberrant co-ordination causes swallowing disorders (dysphagia). In this work, an in vitro model of swallowing was designed to investigate the role of rheology in swallowing and for use as a pre-clinical tool for simulation of different routes to dysphagia. The model is based on the geometry of the human pharynx. Manometry is used for pressure measurements and ultrasonic analysis is performed to analyze the flow profiles and determine shear rate in the bolus, the latter being vital information largely missing in literature. In the fully automated model, bolus injection, epiglottis/nasopharynx movement, and ultrasound transducer positioning can be controlled. Simulation of closing of the airways and nasal cavity is modulated by the software, as is a clamping valve that simulates the upper esophageal sphincter. The actions can be timed and valves opened to different degrees, resembling pathologic swallowing conditions. To validate measurements of the velocity profile and manometry, continuous and bolus flow was performed. The respective velocity profiles demonstrated the accuracy and validity of the flow characterization necessary for determining bolus flow. A maximum bolus shear rate of 80 s−1 was noted for syrup-consistency fluids. Similarly, the manometry data acquired compared very well with clinical studies.

Because of the advantages of the ultrasonic velocity Doppler profiler (UVP), namely in spatiotemporal velocity field measurements and in its applicability for opaque liquids, UVP has a wide field of application in science and industry. The following chapter introduces carefully selected examples of applications covering relatively basic areas of application. The focus of the contents in this chapter is categorized into (1) studies of flow instability and transition (Sect. 5.1), (2) measurements and investigations of liquid metal flows (Sect. 5.2), (3) developments of new rheometry (Sect. 5.3), (4) determinations of rheological properties (Sect. 5.4), (5) studies of magnetic fluids (Sect. 5.5) and (6) gas-liquid two-phase flow (Sect. 5.6), (7) measurements of flowrate in turbidity flows (Sect. 5.7), and (8) -determinations of flows in a deforming tube for biomedical applications (Sect. 5.8). The measurement and post-processing techniques used in this chapter are described in detail in Chaps. 4 and 7, and, detailed explanations of these aspects are omitted in this chapter.

The in-line rheometer concept based on the combination of the ultrasonic velocity profiling (UVP) technique and pressure difference (PD) measurements was utilized for investigating the influence of particle concentration and size distribution on the rheology of particulate suspensions in pipe flow under realistic industrial process conditions. Well defined model suspensions were used, consisting of 11mm and 90mm diameter polyamide particles suspended in rapeseed oil at concentrations ranging from 1 to 25% by volume. The variation of concentration and particle size distribution had the expected effects on the shear viscositiy of the investigated unimodal and bimodal suspensions. The in-line results showed that the investigated suspensions exhibit Sisko flow behavior and demonstrated that the UVP+PD method can be used to determine the flow behavior of complex fluids and suspensions, even at high solid concentrations, under industrial conditions in-line. The obtained inline results were in good agreement with measurement data obtained using a conventional rotational controlled-stress rheometer. Limitations of commercially available transducer technology were identified and other possible sources of inaccuracy of the UVP+PD method were investigated. Several improvements of the UVP+PD measurement method were proposed.

This paper describes a methodology for measuring rheological flow properties in-line, in real-time, based on simultaneous measurements of velocity profiles using an ultrasound velocity profiling (UVP) technique with pressure difference (PD) technology. The methodology allows measurements that are rapid, non-destructive and non-invasive and has several advantages over methods presented previously. The set-up used here allows direct access to demodulated echo amplitude data, thus providing an option to switch between time domain algorithms and algorithms based on FFT for estimating velocities, depending on the signal-to-noise ratio (SNR) and time resolution required. Software based on the MATLAB® graphical user interface (GUI) has been developed and provides a powerful and rapid tool for visualizing and processing the data acquired, giving rheological information in real-time and in excellent agreement with conventional methods. This paper further focuses on crucial aspects of the methodology: implementation of low-pass filter and singular value decomposition (SVD) methods, non-invasive measurements and determination of the wall positions using channel correlation and methods based on SVD. Measurements of sound velocity and attenuation of ultrasound in-line were introduced to increase measurement accuracy and provide an interesting approach to determine particle concentration in-line. The UVP-PD methodology presented may serve as an in-line tool for non-invasive, real-time monitoring and process control. © 2007 Elsevier Ltd. All rights reserved.

The in-line ultrasound Doppler-based UVP-PD rheometry method was evaluated for non-invasive, real-time rheological characterization of complex model- and industrial suspensions. The method is based on the combination of ultrasound velocity profile (UVP) and pressure drop (PD) measurements. Experiments were carried out in pressure driven, steady shear flow at different volumetric flow rates in a flow loop, designed to mimic industrial conditions. Results showed that instantaneous velocity profiles and rheological properties could be monitored in real-time, in-line. A much wider range of model and industrial suspensions was covered compared to what has so far been reported in literature. Investigated suspensions differed in particle sizes, distributions, shapes and suspension characteristics. The agreement was good between shear viscosities measured in-line and off-line using conventional rheometers for particles smaller than the shear gap in the concentric cylinders. The UVP-PD method is applicable to suspensions for which conventional, off-line rheometers fail due to shear gap size restrictions. The UVP-PD method can be a valuable tool for process monitoring since rapid changes in rheology during processing can be monitored in real-time, in-line. © 2007 Elsevier Ltd. All rights reserved.

Ultrasonic velocity profiling with pressure difference (UVP-PD) was demonstrated to be a successful, non-invasive, in-line measurement system for instantaneous velocity and rheological flow profiling of complex, opaque fat blends. Model systems of 25% Akomic, 75% rapeseed oil; and 25% Akomic, 74% rapeseed oil and 1% Grindsted® Crystalliser 110 were compared under real process conditions with UVP-PD. Results indicated that the sample containing the crystalliser had twice the viscosity of the control. These in-line results are in agreement with previous off-line results, and offer the chance to probe the mechanics of fat blend physics under real, dynamic conditions. © 2008 Institute of Food Science and Technology.