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Where precision is paramount in managing temperature and fluid dynamics, micro heat exchangers (MHXs) emerge as indispensable tools. This review investigates the significance of MHX technology, offering readers a comprehensive roapmap from conceptualization to market application. We dissect the nuances of material selection, shedding light on cutting‐edge advancements poised to revolutionize MHX efficiency. Furthermore, we explore how the geometry of MHX influences heat transfer dynamics and pressure drop, providing insights into enhancing the overall effectiveness. We delve into the various types of control instrumentation, offering a detailed analysis of their applicability. Beyond the technical prowess, the economic landscape plays a pivotal role in the adoption of MHX technology. [ABSTRACT FROM AUTHOR]

This article focuses on a noise of aerodynamic origin, generated by the flow over single and multiple rectangular cavities. The paper presents the methodology and results of the conducted numerical simulations of the air flow in a channel with a set of rectangular cavities. The aeroacoustic wave equation was used to determine the acoustic pressure generated by the flow. Various configurations of the cavities made it possible to study the influence of their reciprocal location on the generated sound. The research showed that as the distance between the cavities decreased, the acoustic pressure levels increased. They were several decibels higher than for the single-cavity case. [ABSTRACT FROM AUTHOR]

This paper considers the problem of determining the dissipation energy during the flow of a generalized-displaced fluid in the channels of technological equipment. It is known that during the flow of highly viscous non-Newtonian fluids, the problem of heating this substance arises. This is primarily due to the fact that during the transportation of the material, the dissipation mechanism takes place, which leads to overheating of the material. In its turn, this affects the changes in the physical and chemical properties of the material and the technical and economic indicators of the corresponding equipment. We propose a method for calculating the dissipation energy during the flow of a generalized-displaced fluid in the channels of screw machines. To solve this problem, we used the superposition method to construct fields of larger dimensions from fields of smaller dimensions with different boundary conditions. A channel of flat and rectangular shape is considered. Fluid movement is carried out in the longitudinal and longitudinal-transverse directions of the channel. To calculate the amount of energy dissipation of a generalizeddisplaced fluid, it is necessary to first divide the channel sections into sections with different expressions for the flow rate. At the same time, each of the subareas consists of two curvilinear triangles and one rectangle. The mandatory steps of the calculations are the breakdown of the rectangle of the cross section of the straight channel, and the calculation of the integrals from the derivatives of the velocity. The proposed method allows to calculate the energy of dissipative heat generation when calculating the optimal parameters of technological equipment. [ABSTRACT FROM AUTHOR]

There are few studies on the shape and structure of the channel-type induction heating tundish on multi-physics field. Computational fluid dynamics has been used to study the influence of the structure of the tundish on the macroscopic transport behavior of the tundish with channel induction heating. The results show that increasing the depth of the molten pool is conducive to dynamic behavior of multiphase, the deeper the molten pool, the larger the active area, the longer residence time, the more inclusions removal and the higher ratio of plug to dead volume. Meanwhile, the larger the channel diameter, the more inclusions removal in the receiving chamber and channel. The channel induction heating has enough ability to increase the superheat and temperature compensate for the heat loss caused by the excessive residence time of the molten steel in the tundish. The change in the channel structure is crucial to the macroscopic transport behavior of the fluid. The change in channel diameter has the greatest effect on the multi-physics field in the molten pool.

Purpose. The research purpose is to develop a mathematical model of a pressureless flow in a channel with the occurrence in some areas of overflow layer through the wall. Using this model, it is possible to calculate the overflow layer height and length, as well as the change in flow rate in the channel due to the withdrawal of part of the fluid as a result of the overflow. Methods. The research uses a comprehensive multi-stage analytical approach. Firstly, in order to develop a mathematical model for a pressureless flow in the channel with the occurrence in some areas of overflow layer through the wall, this research analytically determines the dependence of the flow rate through the channel wall based on formulas for calculating the weir discharge coefficient. At the second stage, a mathematical model of a hydraulic mixture pressureless flow in a rectangular channel with an overflow through the wall is developed to determine the parameters and flow regimes of the stream. Findings. The dependences of the dimensionless height of the overflow through the channel wall and the effective critical flow depth on the dimensionless current channel length have been obtained for various values of the acting force parameters and the process parameter of the fluid overflow through the channel wall. This made it possible to study the dynamics of changes in these values along the channel for various values of the specified parameters, and to assess the degree of influence of the relevant factors on the characteristics of the pressureless flow along the channel and the process of fluid overflow through wall. Originality. For the first time, the model of the pressureless flow in the channel is generalized for the case of occurrence in some areas of overflow layer through the wall, when the length and height of the overflow layer are not determined by a hole in the side surface, but are controlled by a decrease in the corresponding flow rate. For the first time, this model makes it possible to calculate the height and length of the overflow layer and the change in the flow rate in the channel due to the withdrawal of part of the fluid as a result of the overflow in cases of overflowing condition of the channel with the stream under unstable and non-calculated flow regimes. Practical implications. The mathematical model and the calculation results can be used to ensure the environmental safety of the logistics systems of mining enterprises, as well as to assess the volume of the environmental pollution in case of overflowing through the wall of the channels of pressureless hydraulic transportation of waste from mineral processing and metallurgical plants. [ABSTRACT FROM AUTHOR]

The pipeline transportation of coal slurries is always subject to a temperature difference between the outdoors environment and the fluid body. As slurries' viscosity is typically temperature dependent, the flow is accompanied by the heat transfer. In this study, we used the CFD method to investigate temperature distributions and flow structures in straight and curved channels, which has not previously been investigated, according to our knowledge. First, the results demonstrate that the cooling process influences the flow structures along the stream. The fluid turns more sharply in the cooler fluid in the curved channel, the streamlines overlap at an earlier position within the bend, and the velocity maximum zone is wider. Cooling also has a significant impact on transverse flow. Because of the higher viscosity of the more cooled fluid and thus the difficulty of shearing the fluid in the stream-wise direction, the vorticity and strength of the vortex flow are greater. The fluid velocity at the central part of the channel points toward the inner wall at the beginning of the bend, resulting in an inner-wall biased temperature distribution, as the heat transfer is partially carried out by the fluid velocity. The central velocity points toward the outer wall at the end of the bend, resulting in the outer-wall biased temperature profile. [ABSTRACT FROM AUTHOR]

In this article we observed the modeling the movement of viscous-plastic material, compressed with indicators that depend on the pressure in the channels of complex geometry of technological equipment. As the material we chose the Bingham fluids with two constant parameters - viscosity and pressure threshold. We consider the flow in the flat channel. The motion of the boundaries is assumed to be purely longitudinal, and the flow field is not longitudinal. The transverse component of the velocity appears due to the dependence of the parameters of the rheological model on pressure. Flow simulation was carried out in two stages. At the first stage, we considered the rheological model of the flow of Bingham material, but without compression. In the second stage, we studied the influence of barotropic compression factor. The superposition method was used when considering the flow model. According to the results of the simulation, we obtained a flow model of nonclassical Bingham material, which can be extended to materials that are compressed and satisfy the conditions of barotropicity. Within the framework of the proposed model, we obtained the equations of zero and the second approximation to determine the characteristics of the Bingham flow in a flat channel. The obtained formulas allow to determine the velocity of the quasi-solid core, which is determined by the degree of deviation of the viscosity and shear threshold, and the average value of the inverse viscosity at the same pressure range. It is established that for long channels in the zero approximation the compressibility does not have a significant effect on the flow, but has an effect only in the second approximation, while the average pressure gradient remains a finite value, ie the pressure difference at the channel ends becomes infinite. For barotropic compressible material, this means that if the pressure at one end of the channel becomes infinite, the density of the material at this end must also become infinite. Thus, when the value of pressure tends to infinity, the value of density remains a finite value. Mathematical description of the flow of viscous-plastic baratropic fluid in the channels of complex geometry of technological equipment allows to establish the dependence of viscosity and limit value of shear stress on pressure with the maximum generalization of parameters. [ABSTRACT FROM AUTHOR]

A procedure of mathematical modeling of the characteristics of gasification of a low-melting hydrocarbon material in the flow of a heated inert gas has been proposed which is based on solving the problem of coupled heat transfer in the gas in the channel and in the region occupied by the solid hydrocarbon material. Dependences of the shape of the boundaries of the solid material on the temperature of a carrier gas and on time have been obtained. Calculation results are compared with experimental results. [ABSTRACT FROM AUTHOR]

The fabrication quality of horizontal fluid channels without supports using SLM is low, which further affects friction loss in channels. In the paper, circular fluid channels with diameters from 2 to 14 mm were built horizontally using 316L SS. The surface roughness on the top inner channel is 50–80 μm, while the rest part is approximately 10 μm. The cylindricity is around 0.2 and circularity is 0.16. The fabrication quality was significantly improved using reduced energy input with a compensation model. Friction factor measurements indicate that 75/Re is still valid in laminar flow regardless of fabrication quality. The friction factor in turbulent flow is 0.0034–0.0137, which is higher than the classical theory. Improved fabrication quality slightly reduces the friction factor. A corrected Colebrook model is developed to predict the friction factors for SLM horizontal fluid channels. Building orientation and fluid path need to be considered for reducing pressure loss.

In the article, on the basis of the comfort reflection method, the bank washout that occurs in the joining area of open channels and its effect on the flow pattern is studied. It is shown that the flow hydraulic parameters depend on the angle of joining of the channels.

The pipeline transportation of coal slurries is always subject to a temperature difference between the outdoors environment and the fluid body. As slurries’ viscosity is typically temperature dependent, the flow is accompanied by the heat transfer. In this study, we used the CFD method to investigate temperature distributions and flow structures in straight and curved channels, which has not previously been investigated, according to our knowledge. First, the results demonstrate that the cooling process influences the flow structures along the stream. The fluid turns more sharply in the cooler fluid in the curved channel, the streamlines overlap at an earlier position within the bend, and the velocity maximum zone is wider. Cooling also has a significant impact on transverse flow. Because of the higher viscosity of the more cooled fluid and thus the difficulty of shearing the fluid in the stream-wise direction, the vorticity and strength of the vortex flow are greater. The fluid velocity at the central part of the channel points toward the inner wall at the beginning of the bend, resulting in an inner-wall biased temperature distribution, as the heat transfer is partially carried out by the fluid velocity. The central velocity points toward the outer wall at the end of the bend, resulting in the outer-wall biased temperature profile.

The fabrication quality of horizontal fluid channels without supports using SLM is low, which further affects friction loss in channels. In the paper, circular fluid channels with diameters from 2 to 14 mm were built horizontally using 316L SS. The surface roughness on the top inner channel is 50–80 μm, while the rest part is approximately 10 μm. The cylindricity is around 0.2 and circularity is 0.16. The fabrication quality was significantly improved using reduced energy input with a compensation model. Friction factor measurements indicate that 75/Re is still valid in laminar flow regardless of fabrication quality. The friction factor in turbulent flow is 0.0034–0.0137, which is higher than the classical theory. Improved fabrication quality slightly reduces the friction factor. A corrected Colebrook model is developed to predict the friction factors for SLM horizontal fluid channels. Building orientation and fluid path need to be considered for reducing pressure loss. [ABSTRACT FROM AUTHOR]

Mechanosensitive signaling has emerged as a mechanism for the regulation of cholangiocyte transport and bile formation. The mechanical effect of fluid-flow, or shear, at the apical membrane of cholangiocytes regulates secretion through a process involving increases in [Ca2+]i and activation of Ca2+-activated Cl- channels. However, the initiating steps translating shear force to increases in intracellular calcium concentration ([Ca2+]i) are unknown. Transient receptor potential vanilloid member 4 (TRPV4), a nonselective cation channel present in the apical membrane of cholangiocytes, has been proposed as a potential mechanosensor. The aim of the present studies was to determine the potential role of TRPV4 in initiating mechanosensitive signaling in response to fluid-flow in cholangiocytes. TRPV4 expression was confirmed in both small and large mouse cholangiocytes. Exposure of cells to either fluid flow or specific TRPV4 pharmacological agonists rapidly increased both [Ca2+]i and membrane cation currents. Both flow- and agonist-stimulated currents displayed identical biophysical properties and were inhibited in the presence of TRPV4 antagonists or in cells after transfection with TRPV4 small interfering RNA. Transfection of mouse cholangiocytes with a TRPV4-enhanced green fluorescent protein construct increased the expression of TRPV4 and the magnitude of flow-stimulated currents. A specific TRPV4 agonist significantly increased the biliary concentration of ATP and bile flow in live mice when administered intravenously and increased ATP release from cholangiocyte monolayers when applied exogenously. The findings are consistent with a model in which activation of cholangiocyte TRPV4 translates shear force into an acute rise in membrane cation permeability, [Ca2+]i, ATP release, and bile flow. Understanding the role of mechanosensitive transport pathways may provide novel insights to modulate bile flow for the treatment of cholestatic liver disorders. NEW & NOTEWORTHY These studies functionally characterize TRPV4 as a mechanosensitive channel in mouse cholangiocytes. By mediating a rapid rise in intracellular Ca2+, necessary for Ca2+-dependent secretion, TRPV4 represents a mechanosensor responsible for translating fluid flow into intracellular signaling and biliary secretion. Furthermore, intravenous infusion of a specific TRPV4 agonist increases bile flow in live mice. Understanding the role of TRPV4 in mechanosensitive transport pathways may provide novel insights to modulate bile flow during cholestasis. [ABSTRACT FROM AUTHOR]

Copyright of Science-Based Technologies is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, The FLUNET numerical simulation software was used to establish two-dimensional model, loading velocity, pressure and wall roughness. The flow field of the channel was calculated by using FLUENT numerical simulation software to calculate the flow field of the same flow rate and section velocity profile. The relationship between flow rate, flow velocity and roughness was studied in order to provide the basis for choosing the roughness coefficient correctly in practice. The results show that for the concrete bag lining channel, flow velocity and discharge are the factors of roughness. Through data correlation analysis, roughness is negatively correlated with velocity and discharge,the velocity gradually increases along the direction of the channel's bottom, but the maximum velocity occurs below the water surface and the lateral flow from the channel wall to the central flow, resulting in a larger velocity concentrated in the middle area. [ABSTRACT FROM AUTHOR]

Copyright of Science-Based Technologies is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We study flow of substance in a channel of network which consists of nodes of network and edges which connect these nodes and form ways for motion of substance. The channel can have arbitrary number of arms and each arm can contain arbitrary number of nodes. The flow of substance is modeled by a system of ordinary differential equations. We discuss first a model for a channel which arms contain infinite number of nodes each. For stationary regime of motion of substance in such a channel we obtain probability distributions connected to distribution of substance in any of channel’s arms and in entire channel. Obtained distributions are not discussed by other authors and can be connected to Waring distribution. Next, we discuss a model for flow of substance in a channel which arms contain finite number of nodes each. We obtain probability distributions connected to distribution of substance in the nodes of the channel for stationary regime of flow of substance. These distributions are also new and we calculate corresponding information measure and Shannon information measure for studied kind of flow of substance.

This paper presents a μ -Coriolis mass flow sensor with resistive readout. Instead of measuring a net displacement such as in a capacitive readout, a resistive readout detects the deformation of the suspended micro-fluidic channel. It allows for actuation at much higher amplitudes than for a capacitive readout, resulting in correspondingly larger Coriolis forces in response to fluid flow. A resistive readout can be operated in two actuation vibrational modes. A capacitive readout can only be operated in one of these two modes, which is more sensitive to external disturbances. Three types of devices have been realized. We present measurement results for all three devices. One device clearly outperforms the other two, with a flow sensitivity of 2.22 °/(g·h−1) and a zero-flow stability of 0.02 g·h−1 over 30 min. Optimization of the metal strain gauges and/or implementation of poly-Silicon strain gauges could further improve performance.

Introduction. The problems of simulating viscoplastic longitudinal and cross-sectional flow of non-Newtonian fluids are overviewed. Materials and methods. For the first time the superposition method by expressing the components of the stress tensor for building flow fields with higher dimension from flow fields with lower dimension with various boundary conditions when rheological parameters change depending on pressure was used. The flows in the channel are categorized by velocity and pressure values in each point of the section. Results.The theoretical methods for simulating flows of non-Newtonian fluids in channels of different geometry with moving bounds and pressure drop on channel edges with respect to functional connections between main process parameters are described using the superposition method. It is shown that longitudinal and cross-sectional are reduced to the collection of one-dimensional longitudinal flows of the same type which allow to describe three-dimensional isothermal in rectangular channel and two-dimensional flows in flat channels with different channel aspect ratio. The received theoretical two- and three-dimensional model of viscous flows in channels with basic geometry allow to research main regularities of the process and to establish optimal macro-kinetic and macro-dynamic flow characteristics of non-Newtonian materials which are aimed at reducing energy costs and material consumption of food processing equipment. Conclusion.The developed and theoretically reasonable three-dimensional models flows of non-Newtonian fluids in channels allow to perform qualitatively new design of food processing equipment which allows to reduce energy costs and material consumption.

Copyright of Science-Based Technologies is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The concepts and methods of the visual representation of fluid dynamics computations of vortical flows are studied. Approaches to the visualization of vortical flows based on the use of various definitions of a vortex and various tests for its identification are discussed. Examples of the visual representation of solutions to some fluid dynamics problems related to the computation of vortical flows in jets, channels, and cavities and of the computation of separated flows occurring in flows around bodies of various shapes are discussed. [ABSTRACT FROM AUTHOR]

Theon the basis of the numerical solution of the equations of Navier-Stokes. The numerical solution is obtained with a finite volumemethod in the Code Saturne software package. Adequacy of the implemented model was proved by comparing the numerical solutionforVoskoboinik.spherical [ABSTRACT FROM AUTHOR]

This paper deals with the effect of nanofluid and inclined magnetic field on peristaltic transport of a fourth grade fluid model. Mathematical modelling of two dimensional fourth grade fluid along with nanofluid model are given for channel. Assumptions of long wave length are employed to simplify the governing equations of momentum, temperature, and nano particle volume fraction. The exact solutions of temperature and nano particle volume fraction are calculated. Analytical solution is carried out to calculate the solution of stream function. Pressure rise and pressure gradient on the channel walls have been computed numerically. The graphical results are discussed to see the effects of various emerging parameters on different wave forms. [ABSTRACT FROM AUTHOR]

Introduction. The problems of simulating viscoplastic longitudinal and cross-sectional flow of non-Newtonian fluids are overviewed. Materials and methods. For the first time the superposition method by expressing the components of the stress tensor for building flow fields with higher dimension from flow fields with lower dimension with various boundary conditions when rheological parameters change depending on pressure was used. The flows in the channel are categorized by velocity and pressure values in each point of the section. Results. The theoretical methods for simulating flows of non-Newtonian fluids in channels of different geometry with moving bounds and pressure drop on channel edges with respect to functional connections between main process parameters are described using the superposition method. It is shown that longitudinal and cross-sectional are reduced to the collection of one-dimensional longitudinal flows of the same type which allow to describe three-dimensional isothermal in rectangular channel and two-dimensional flows in flat channels with different channel aspect ratio. The received theoretical two- and three-dimensional model of viscous flows in channels with basic geometry allow to research main regularities of the process and to establish optimal macro-kinetic and macro-dynamic flow characteristics of non-Newtonian materials which are aimed at reducing energy costs and material consumption of food processing equipment. Conclusion. The developed and theoretically reasonable three-dimensional models flows of non-Newtonian fluids in channels allow to perform qualitatively new design of food processing equipment which allows to reduce energy costs and material consumption. [ABSTRACT FROM AUTHOR]

The analysis of energy balance equation for viscous laminar flow of fluid or gas in the cylindrical channel in the area (zone) of warm-up bounded along the longitudinal coordinate is made. It was found that at laminar flow of fluid or gas in a round pipe, in each warm-up area bounded along the longitudinal coordinate there are the areas of direct and reverse flows separated by a plane that is a locus of points where temperature is maximal for each fixed value of radial coordinate r. [ABSTRACT FROM AUTHOR]

Relations for calculating a shear flow in the centrifugal impeller channels are presented. The results of three-dimensional flow visualization in the centrifugal forces field show a satisfactory agreement with calculation data within a wide range of centrifugal pump design and operational parameters. [ABSTRACT FROM AUTHOR]

Experimentally observed self-oscillations of a cylinder in a plane channel whose width is slightly greater than the cylinder diameter under the impact of the incoming fluid flow are modeled. Within the model of a nonseparated potential flow around the cylinder, the coefficients of added mass of the cylinder are calculated with the help of the generalized method of images. When the cylinder touches the channel wall, the circulation sign changes, and its value is determined by the boundary element method and the no-slip condition for the fluid at the contact point. The Joukowski force and the drag force proportional to the square of velocity are taken into account in the equations of motion of cylinder. [ABSTRACT FROM AUTHOR]

We experimentally confirmed the effect when the wave resistance of rough-wall plane channels, generated while the walls are streamlined by a supersonic gas flow, reaches the extreme values. The experiments were conducted on a differential setup by comparing the tests of flat and round sonic nozzles. The results of the experiment justified the developed method of calculating the wave resistance of the plane channel with sawtooth wall relief. [ABSTRACT FROM AUTHOR]

A computational study is performed on a three-dimensional turbulent flow and heat transfer in a rotating rectangular channel with an aspect ratio of 10:1, oriented 120° from the direction of rotations. Entropy generation due to heat transfer and fluid friction is computed and reported. To examine the influence of rotation number and density ratio on volumetric entropy generation rate, rotation number and density ratio are varied in the simulations. A numerical scheme employing a control volume approach is introduced to solve the governing equations of transport. A constant heat flux boundary condition at the leading and trailing edges of the channel is considered to resemble the blade heating. It is found that the rotation number and density ratio have a significant effect on the entropy generation rate in the channel. In this case, increasing the density ratio enhances the entropy generation rate, whereas increasing the rotation number modifies the trend of the entropy generation rate in the channel. [ABSTRACT FROM AUTHOR]