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R P Chhabra - One of the best experts on this subject based on the ideXlab platform.
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Effect of a rotating cylinder on the flow of a Bingham Plastic Fluid in T-junction: Momentum and heat transfer characteristics
International Journal of Heat and Mass Transfer, 2019Co-Authors: Anamika Maurya, Naveen Tiwari, R P ChhabraAbstract:Abstract The present numerical work investigates the momentum and heat transfer characteristics of a Bingham Plastic Fluid in a rectangular T-channel. A rotating cylinder which is placed in a T-junction mimics the behaviour of a rotating valve to regulate the Fluid flow and enthalpy in the two branches of the channel. Numerical simulations are carried out over a wide range of conditions (based on the cylinder diameter): Reynolds number ( 10 - 2 ⩽ Re ≤ 40 ) , Bingham number ( 10 - 2 ⩽ Bn ≤ 20 ) , Prandtl number ( 10 ⩽ Pr ≤ 100 ) and rotational velocity of the cylinder ( - 5 ⩽ α ≤ 5 ) where α is the circumferential velocity normalized by the inlet velocity. Extensive results are presented in the form of streamline patterns, isotherm contours and yielded/unyielded regions in the vicinity of the T-junction. In particular, the major thrust of this study is to predict the hydrodynamic forces and torque exerted on the cylinder, flow split ratio (i.e., flow rates in the two outlet branches), critical Bingham number (beyond which no flow separation occurs). Also, the outlet temperatures, enthalpy gain, distribution of Nusselt number over the cylinder surface and its average value as a function of the governing dimensionless parameters have been investigated. The present results show that the rotation of the cylinder can aid or suppress the formation of the recirculation zones effectively which appear on the left wall of the main branch and lower wall of the side branch depending upon the Reynolds number while it always suppresses the cylinder wake. As expected, the Bingham number stabilizes the flow by suppressing the recirculation zone while the Reynolds number tends to promote it. The flow split ratio is found to be significantly affected by the direction of the cylinder rotation. The cylinder rotation also shows a strong impact on the mean values of the hydrodynamic forces and torque. The temperature of the exiting relative streams is seen to be higher for the lower Reynolds and Prandtl numbers, and higher Bingham numbers while cylinder rotation shows a weak effect. The enthalpy gain by the main branch is found to be significantly affected by all the parameters. It has also been observed that the rate of heat transfer is higher for a clockwise rotating cylinder than in the case of an anticlockwise rotating cylinder.
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Effect of orientation on the drag of a cone settling in a Bingham Plastic Fluid
Particuology, 2019Co-Authors: Pragya Mishra, Anurag Kumar Tiwari, R P ChhabraAbstract:Abstract Effects of the orientation and apex angle on the settling velocity of conical particles in Bingham Plastic Fluids are numerically investigated over a Reynolds number range of 1 ≤ Re ≤ 100, Bingham number range of 0 ≤ Bn ≤ 100, and cone angle range of 20° ≤ α ≤ 150°. Governing equations (of continuity and momentum) are solved numerically using the finite element method to obtain velocity and pressure fields that are postprocessed to obtain values of the drag coefficient. Furthermore, the effect of cone orientation on the flow field is visualized and explored in terms of streamline contours and the morphology of yielded/unyielded regions. Finally, the obtained values of drag are correlated via a simple predictive expression in terms of the modified Reynolds number. The effect of the cone angle on drag is found to be moderate because the drag force acting on the lateral surface is a small fraction of the overall drag.
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natural convection in Bingham Plastic Fluids from an isothermal spheroid effects of Fluid yield stress viscous dissipation and temperature dependent viscosity
Korea-australia Rheology Journal, 2017Co-Authors: Sanjay Kumar Gupta, Anoop K. Gupta, R P ChhabraAbstract:In this work, the buoyancy-induced convection from an isothermal spheroid is studied in a Bingham Plastic Fluid. Extensive results on the morphology of approximate yield surfaces, temperature profiles, and the local and average Nusselt numbers are reported to elucidate the effects of the pertinent dimensionless parameters: Rayleigh number, 102 ≤ Ra ≤ 106; Prandtl number, 20 ≤ Pr ≤ 100; Bingham number, 0 ≤ Bn ≤ 103, and aspect ratio, 0.2 ≤ e ≤ 5. Due to the Fluid yield stress, Fluid-like (yielded) and solid-like (unyielded) regions coexist in the flow domain depending upon the prevailing stress levels vis-a-vis the value of the Fluid yield stress. The yielded parts progressively grow in size with the rising Rayleigh number while this tendency is countered by the increasing Bingham and Prandtl numbers. Due to these two competing effects, a limiting value of the Bingham number (Bn max) is observed beyond which heat transfer occurs solely by conduction due to the solid-like behaviour of the Fluid everywhere in the domain. Such limiting values bear a positive dependence on the Rayleigh number (Ra) and aspect ratio (e). In addition to this, oblate shapes (e 1) impede it. Finally, simple predictive expressions for the maximum Bingham number and the average Nusselt number are developed which can be used to predict a priori the overall heat transfer coefficient in a new application. Also, a criterion is developed in terms of the composite parameter Bn∙Gr-1/2 which predicts the onset of convection in such Fluids. Similarly, another criterion is developed which delineates the conditions for the onset of settling due to buoyancy effects. The paper is concluded by presenting limited results to delineate the effects of viscous dissipation and the temperature-dependent viscosity on the Nusselt number. Both these effects are seen to be rather small in Bingham Plastic Fluids.
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the motion of a rotating circular cylinder in a stream of Bingham Plastic Fluid
Journal of Non-newtonian Fluid Mechanics, 2016Co-Authors: Pooja Thakur, Naveen Tiwari, Shikhar Mittal, R P ChhabraAbstract:Abstract In this work, two-dimensional, steady flow of incompressible Bingham Plastic Fluids past a rotating circular cylinder has been studied. The continuity and momentum equations have been solved numerically over the range of conditions as follows: 0.1 ≤ Re ≤ 40; Bingham number, 0 ≤ Bn ≤ 103 and non-dimensional rotational velocity 0 ≤ α ≤ 5. The objective of the detailed numerical study is to elucidate the effects of Reynolds number, Bingham number and rotational velocity on the yield surfaces, the drag and lift coefficients, and torque acting on the rotating cylinder. The present drag results have been correlated with the modified Reynolds number and rotational velocity to interpolate the intermediate values of Bingham number. In additional, shear rate and yielded/unyielded contours, and streamlines in the vicinity of the cylinder are also presented for detailed visualization of the flow field. The critical Bingham number, denoting the cessation of the flow detachment from the surface of the rotating cylinder, has been plotted as a function of the Reynolds number, and the rotational velocity is shown to suppress the propensity for flow separation.
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Mixed convection from a spheroid in Bingham Plastic Fluids: Effect of buoyancy-assisted flow
Numerical Heat Transfer Part A: Applications, 2016Co-Authors: Anoop K. Gupta, R P ChhabraAbstract:ABSTRACTIn this work, laminar mixed convection from an isothermal spheroidal particle immersed in a Bingham Plastic Fluid is studied numerically in the buoyancy-assisted regime. The results reported herein encompass the following ranges of conditions: Reynolds number, 0.1 ≤ Re ≤ 100; Prandtl number, 10 ≤ Pr ≤ 100; Bingham number, 0 ≤ Bn ≤ 100; Richardson number, 0 ≤ Ri ≤ 8; and aspect ratio of the spheroid, 0.2 ≤ e ≤ 5. In particular, consideration is given to the effect of shape and orientation of the particle on the detailed flow and temperature fields (in terms of streamlines, iso-vorticity, and isotherm contours), morphology of the yielded–unyielded regions, and the local and surface-averaged Nusselt number. All else being equal, the propensity for flow separation is seen to be greater for oblates (e 1). In both cases, this reduces with the increasing Bingham number and/or the Richardson number. Both drag coefficient and the Nusselt number show a positive dependence on...
Anoop K. Gupta - One of the best experts on this subject based on the ideXlab platform.
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natural convection in Bingham Plastic Fluids from an isothermal spheroid effects of Fluid yield stress viscous dissipation and temperature dependent viscosity
Korea-australia Rheology Journal, 2017Co-Authors: Sanjay Kumar Gupta, Anoop K. Gupta, R P ChhabraAbstract:In this work, the buoyancy-induced convection from an isothermal spheroid is studied in a Bingham Plastic Fluid. Extensive results on the morphology of approximate yield surfaces, temperature profiles, and the local and average Nusselt numbers are reported to elucidate the effects of the pertinent dimensionless parameters: Rayleigh number, 102 ≤ Ra ≤ 106; Prandtl number, 20 ≤ Pr ≤ 100; Bingham number, 0 ≤ Bn ≤ 103, and aspect ratio, 0.2 ≤ e ≤ 5. Due to the Fluid yield stress, Fluid-like (yielded) and solid-like (unyielded) regions coexist in the flow domain depending upon the prevailing stress levels vis-a-vis the value of the Fluid yield stress. The yielded parts progressively grow in size with the rising Rayleigh number while this tendency is countered by the increasing Bingham and Prandtl numbers. Due to these two competing effects, a limiting value of the Bingham number (Bn max) is observed beyond which heat transfer occurs solely by conduction due to the solid-like behaviour of the Fluid everywhere in the domain. Such limiting values bear a positive dependence on the Rayleigh number (Ra) and aspect ratio (e). In addition to this, oblate shapes (e 1) impede it. Finally, simple predictive expressions for the maximum Bingham number and the average Nusselt number are developed which can be used to predict a priori the overall heat transfer coefficient in a new application. Also, a criterion is developed in terms of the composite parameter Bn∙Gr-1/2 which predicts the onset of convection in such Fluids. Similarly, another criterion is developed which delineates the conditions for the onset of settling due to buoyancy effects. The paper is concluded by presenting limited results to delineate the effects of viscous dissipation and the temperature-dependent viscosity on the Nusselt number. Both these effects are seen to be rather small in Bingham Plastic Fluids.
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Mixed convection from a spheroid in Bingham Plastic Fluids: Effect of buoyancy-assisted flow
Numerical Heat Transfer Part A: Applications, 2016Co-Authors: Anoop K. Gupta, R P ChhabraAbstract:ABSTRACTIn this work, laminar mixed convection from an isothermal spheroidal particle immersed in a Bingham Plastic Fluid is studied numerically in the buoyancy-assisted regime. The results reported herein encompass the following ranges of conditions: Reynolds number, 0.1 ≤ Re ≤ 100; Prandtl number, 10 ≤ Pr ≤ 100; Bingham number, 0 ≤ Bn ≤ 100; Richardson number, 0 ≤ Ri ≤ 8; and aspect ratio of the spheroid, 0.2 ≤ e ≤ 5. In particular, consideration is given to the effect of shape and orientation of the particle on the detailed flow and temperature fields (in terms of streamlines, iso-vorticity, and isotherm contours), morphology of the yielded–unyielded regions, and the local and surface-averaged Nusselt number. All else being equal, the propensity for flow separation is seen to be greater for oblates (e 1). In both cases, this reduces with the increasing Bingham number and/or the Richardson number. Both drag coefficient and the Nusselt number show a positive dependence on...
R.a.j. Van Ostayen - One of the best experts on this subject based on the ideXlab platform.
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Rheological texture in a journal bearing with magnetorheological Fluids
Journal of Magnetism and Magnetic Materials, 2020Co-Authors: S.g.e. Lampaert, Federico Quinci, R.a.j. Van OstayenAbstract:This paper discusses a new type of hybrid journal bearing in which a magnetorheological Fluid is used in combination with local magnetic fields, such that the hydrodynamic and hydrostatic working regimes are not compromised. This demonstrates the potential of using the concept of rheological texture in bearings. The performance of this new type of bearing is assessed via Finite Element Modelling (FEM) in which the behaviour of the Fluid film is described by the ideal Bingham Plastic Fluid model. Both the yield stress and the viscosity increase as a function of the magnetic field.
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Lubrication theory for Bingham Plastics
Tribology International, 2020Co-Authors: S.g.e. Lampaert, R.a.j. Van OstayenAbstract:Abstract The rheological behavior of many lubricants used in hydrodynamic bearings can reasonably be modeled using the Bingham Plastic material model. This behavior is characterized by a strong discontinuity, from a pure solid state to a viscous Fluid state depending on the local shear stress. In literature three methods have been presented to model a Bingham Plastic lubricated film. A full CFD and thus expensive, numerical simulation has been used. A general Reynolds equation based simulation has been used, however with a less accurate numerical regularization of the material discontinuity. Or a general Reynolds equation based simulation has been used, but with a severe reduction of the geometric complexity. In this paper, an ’exact’ thin film lubrication simulation for a Bingham Plastic Fluid is presented. The model is said to be exact in the sense that it requires no additional approximations to those used in the derivation of the general Reynolds equation, and requires no numerical regularization of the Bingham Plastic Fluid model and can still be used on any lubricating film geometry. Simulations on both infinite and finite journal bearings shows that the results of this new method are in good accordance with literature, demonstrating the validity of the method.
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Load and stiffness of a hydrostatic bearing lubricated with a Bingham Plastic Fluid
Journal of Intelligent Material Systems and Structures, 2019Co-Authors: S.g.e. Lampaert, R.a.j. Van OstayenAbstract:Using a smart Fluid, for example, magnetorheological or electrorheological, in a hydrostatic bearing gives the possibility to actively change the bearing properties during operation. This work pres...
Yonggang Wang - One of the best experts on this subject based on the ideXlab platform.
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Bingham Plastic Fluid flow model for ceramic tape casting
Materials Science and Engineering: A, 2002Co-Authors: Guangneng Zhang, Yonggang WangAbstract:Abstract Multilayer ceramic substrates with conductor traces are attracting a great deal of attention for their ability to increase packaging density for large-scale integration circuits. Currently one of the main methods used for the manufacture of flat ceramic packages with precise thickness control and consistency is the tape casting technique. It is crucial that the green tape thickness is controlled precisely and consistently. The Fluid mechanics associated with the flow of a ceramic slurry during the tape casting process is analyzed. The flow of the slurry onto the casting surface can be modeled as a two-dimensional Fluid flow through a parallel channel. The material of this study is an organic-bonded glass–alumina slurry and is modeled as a Bingham Plastic Fluid with a yield stress. The proposed model accurately described the Fluid flow characteristics of the process, and has good agreement with experimental results.
Chiang C. Mei - One of the best experts on this subject based on the ideXlab platform.
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Long waves in shallow water over a layer of Bingham-Plastic Fluid-mud. I: Physical aspects
International Journal of Engineering Science, 1993Co-Authors: Liu Ko-fei, Chiang C. MeiAbstract:This theoretical inquiry is motivated by the need to better understand wave/seabed interaction along muddy coasts. Since under certain conditions hyperconcentrated Fluid-mud flows are known to remain laminar and can be approximately described by the Bingham Plastic model, we study the transient motion in a two-layer system with a Bingham Fluid lying under water. Attention is focused on the implications of the yield stress which is a distinguishing feature of the Bingham Plastic model.
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long waves in shallow water over a layer of Bingham Plastic Fluid mud ii mathematical derivation of long wave equations
International Journal of Engineering Science, 1993Co-Authors: Liu Kofei, Chiang C. MeiAbstract:In this part we give a systematic derivation of the long wave equations in water and Fluid mud layers. Based on the assumption of small depth/wave-length ratio, a perturbation analysis is carried out for a Fluid-mud modeled by a generalized Bingham Fluid with two viscosities. The results confirm the heuristic derivation given in Part I, and clarifies the regime of validity.