Computational Modeling of Enhanced Laminar Flow Heat Transfer in Viscoplastic Fluids in Corrugated-Plate Channels

2002 ◽  
Author(s):  
Hossam M. Metwally ◽  
Raj M. Manglik
Keyword(s):  
Heat Transfer ◽  
Yield Stress ◽  
Power Law ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Bingham Plastic ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Colburn Factor ◽  
Power Law Index

The enhanced heat transfer in laminar viscoplastic, shear thinning, Herschel-Bulkley fluid flows in sinusoidal corrugated-plate channels is investigated. With uniform-temperature plate walls, periodically developed flows are considered for a wide range of flow rates (10 ≤ Reg ≤ 700) and pseudoplastic flow behavior indices (n = 0.54, 0.8, and 1.0; the latter representing a Bingham plastic). The effects of fluid yield stress are simulated for the case where τy = 1.59 N/m2, representing a 0.5% xantham gum aqueous solution. Typical velocity and temperature distributions, along with extended results for isothermal friction factor ƒ and Colburn factor j are presented. The effect of the yield stress is found to be most dominant at low Reg regardless of the power law index n, and the recirculation or swirl in the wall trough regions is weaker than in the cases of Newtonian and power-law liquids. At higher Reg, the performance of the Herschel-Bulkley fluid asymptotically approaches that of the non-yield-stress power-law fluid. At low Reg, the yield stress increases ƒ by an order of magnitude and j is enhanced because of the higher wall gradients imposed by the plug-like flow field. The relative heat transfer enhancement, represented by the ratio (j/ƒ), and the role of the fluid yield stress and shear-thinning (or pseudoplastic) behaviors are also discussed.

Heat Transfer Enhancement in Annular Shear-Thinning Flows Over a Sudden Pipe Expansion

2017 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Power Law ◽  
Shear Thinning ◽  
Diameter Ratio ◽  
Transfer Enhancement ◽  
Heat Transfer Augmentation ◽  
Prandtl Numbers ◽  
Power Law Index ◽  
The Impact

Heat transfer enhancement in suddenly expanding annular pipe flows of a shear-thinning non-Newtonian fluid is studied within the steady laminar flow regime. Conservation of mass, momentum, and energy equations, along with the power-law constitutive model are numerically solved. The impact of inflow inertia, annular-nozzle-diameter-ratio, k, power-law index, n, and Prandtl numbers, is reported for: Re = {50, 100}, k = {0, 0.5, 0.7}; n = {1, 0.8, 0.6}; and Pr = {1, 10, 100}. Heat transfer enhancement downstream of the expansion plane, i.e., Nusselt numbers, Nu, higher than the fully developed value, in the downstream pipe, is observed only for Pr = 10 and 100. Higher Prandtl numbers, power-law index values, and annular diameter ratios, in general, reflect a more dramatic heat transfer augmentation downstream of the expansion plane. Heat transfer augmentation for Pr = 10 and 100, is more dramatic for suddenly expanding annular flows, in comparison with suddenly expanding pipe flow. For a given annular diameter ratio and Reynolds numbers, increasing the Prandtl number from Pr = 10 to Pr = 100, always results in higher peak Nu values, for both Newtonian and shear-thinning non-Newtonian flows.

Shear thinning of the bulk metallic glass forming alloy Zr41.2 Ti13.8 Cu12.5 Ni10.0 Be22.5 close to the liquidus temperature.

2003 ◽  
Vol 806 ◽  
Author(s):  
Tyler Shaw ◽  
Christopher Way ◽  
Ralf Busch
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Power Law ◽  
Liquidus Temperature ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Shear Rates ◽  
Glass Forming ◽  
Power Law Index ◽  
Type Response

ABSTRACTThe viscous properties of the multi component Zr41.2 Ti13.8 Cu12.5 Ni10.0 Be22.5 bulk metallic glass forming alloy was studied above the liquidus temperature. A shear thinning behavior for the molten alloy has been discovered. The shear thinning behavior can be characterized as a power law fluid with a power-law index of -0.5. Additionally, at low shear rates and temperatures near the liquidus temperature a visco-elastic type response in the flow behavior is observed.

Flow Inertia and Heat Transfer in Suddenly Expanding Annular Shear-Thinning Flows

2017 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Heat Transfer ◽  
Power Law ◽  
Shear Thinning ◽  
Heat Transfer Augmentation ◽  
Flow And Heat Transfer ◽  
Prandtl Numbers ◽  
Power Law Index ◽  
Annular Pipe ◽  
Flow Inertia ◽  
The Impact

The impact of flow inertia on flow and heat transfer in suddenly expanding annular pipe flows of a shear-thinning non-Newtonian fluid is studied within the steady laminar flow regime. The equations governing conservation of mass, momentum, and energy, along with the power-law constitutive model are numerically solved using a finite-difference numerical scheme. The influence of inflow inertia, annular-nozzle-diameter-ratio, k, power-law index, n, and Prandtl numbers, is reported for: Re = {50, 100}, k = {0, 0.5}; n = {1, 0.6}; and Pr = {1, 10, 100}. Heat transfer augmentation, downstream the plane of expansion, is only observed for Pr = 10 and 100. The extent and intensity of recirculation in the corner region, increases with inflow inertia. Higher Reynolds and Prandtl numbers, power-law index values, and annular diameter ratios, in general, reflect a more dramatic heat transfer augmentation downstream of the expansion plane.

A Computational Study of Enhanced Heat Transfer in Laminar Flows of Non-Newtonian Fluids in Corrugated-Plate Channels

2000 ◽  
Author(s):  
Hossam M. Metwally ◽  
Raj M. Manglik
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Swirl Flow ◽  
Laminar Flows ◽  
Enhanced Heat Transfer ◽  
Uniform Wall Temperature ◽  
Wide Range ◽  
Uniform Wall

Abstract The enhanced heat transfer behavior of laminar shear-thinning, power-law fluid flows in sinusoidal corrugated-plate channels is investigated. With duct plates at uniform wall temperature, periodically developed flows are considered for a wide range of channel corrugation aspect ratio (0 ≤ γ ≤ 1), flow rates (10 ≤ Reg ≤ 1500), and pseudo-plastic flow behavior indices (n = 0.5, 0.8, and 1.0). Typical velocity and temperature distributions, along with extended results for isothermal friction factor f and Collburn factor j are presented. The enhanced forced convection is found to be strongly influenced by γ, and the flow field displays two distinct regimes: undisturbed laminar or no swirl, and swirl flow regimes. In the no-swirl regime, behavior similar to that in fully developed straight duct flows with no cross-stream disturbance is obtained. The shear-thinning nature of the fluid, however, decreases f and enhances j. In the swirl regime, flow separation and reattachment in the corrugation troughs generates transverse vortices that grow with Reg and γ. The transition to this regime is also seen to depend on Reg, γ, and n, and in shear-thinning flows, it occurs at a lower Reg. The combined effects of corrugated plate geometry and non-Newtonian fluid rheology produce a heat transfer enhancement, as measured by the factor j/f, of over 3.3 times that in a flat-plate channel depending upon γ, n, and Reg.

Influence of a Yield-Shear-Thinning Rheology on the Flow Behavior of Submerged Annular Jets

2020 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Flow Field ◽  
Power Law ◽  
Numerical Solutions ◽  
Flow Behavior ◽  
Shear Thinning ◽  
Momentum Conservation ◽  
Recirculation Region ◽  
Substantial Impact ◽  
Laminar Jet ◽  
Power Law Index

Abstract The flow structure and decay characteristics of submerged annular yield-pseudoplastic jets are investigated. Numerical solutions to the governing mass and momentum conservation equations, along with the Herschel-Bulkley rheological model, are obtained using a finite-difference scheme. A parametric study is implemented to investigate the effects of annular nozzle diameter ratio, κ, the power-law index, n, and yield number, Y, over the following range: κ = {0, 0.5}; n = {1, 0.6}; and Y = {0, 1, 5}. The Reynolds number was fixed at Re = 100, which ensured steady and laminar jet flow conditions throughout the whole flow field. The selected yield number and power-law index values allowed for the investigation of the presence of yield stress and shear-thinning effects on the resulting structure and evolution of the flow field. The results demonstrate the substantial impact of the inflow conditions and rheology on the annular jet evolution, and on the extent of the outer recirculation region and recirculation strength of both the outer and central regions.

Numerical Investigation of Power-Law Fluid Flows and Heat Transfer inside of Curved Duct under Aiding Thermal Buoyancy

2018 ◽  
Vol 16 ◽  
pp. 84-95 ◽  
Author(s):  
Fayçal Bouzit ◽  
Houssem Laidoudi ◽  
Bilal Blissag ◽  
Mohamed Bouzit ◽  
Abdellah Guenaim
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Power Law ◽  
Flow Behavior ◽  
Two Dimensions ◽  
Thermal Buoyancy ◽  
Curved Duct ◽  
Ansys Cfx ◽  
Power Law Fluids ◽  
Power Law Index

This paper deals with a numerical investigation in order to predict correctly the combined effects of aiding thermal buoyancy and rheological flow behavior of power-law fluids on downward flow and heat transfer rate inside of 180° curved duct. The governing equations involving the momentum, continuity and the energy are solved in two-dimensions using the package called ANSYS-CFX. The computational results are depicted and discussed for the range of conditions as:Re= 40 to 1000,Ri= 0 to-1 andn= 0.4 to 1.2 at fixed value of Prandt number ofPr= 1. To interpret the found results, the flow structure and temperature field are shown in form of streamlines and isotherm contours. The average Nusselt number of the inner and outer walls of curved channel is calculated to determine the role of Reynolds number, Richardson number and power-law index. It is found that increase in strength of aiding buoyancy creates a counter rotating region in angle of 90 degrees of the duct.

Mixed Convection Heat Transfer of Shear-Thinning Fluids around Confined Square Cylinder at Low Reynolds Number

2018 ◽  
Vol 384 ◽  
pp. 12-20
Author(s):  
Houssem Laidoudi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Shear Thinning ◽  
Square Cylinder ◽  
Thermal Buoyancy ◽  
Shear Thinning Fluids ◽  
Power Law Index

This work deals with the effect of thermal buoyancy on momentum and heat transfer characteristics of confined square cylinder submerged in Non Newtonian shear-thinning fluids. In two-dimension, the governing equations are solved by using the commercial code ANSYS-CFX. The effects of thermal buoyancy and power-law index, n, on the non-dimensional Drag coefficient and Nusselt number are studied for the conditions: Ri = 0 to 1, n = 0.3 to 0.9, Re = 40, Pr = 1 and blockage ratio β = 1/4. The detailed flow and temperature field are presented in terms of streamlines and isotherm contours. It is found that for all values of Richardson number increase in the power-law index increases the total drag coefficient and decreases the non-dimensional Nusselt number.

Free Convection in Viscoplastic Fluid due to Partial Bi-Heating From Bottom

2016 ◽  
Author(s):  
Naushad Hasin Khan ◽  
M. A. Hassan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Rayleigh Number ◽  
Free Convection ◽  
Yield Stress ◽  
Power Law ◽  
Viscoplastic Fluid ◽  
Onset Of Convection ◽  
Square Enclosure ◽  
Power Law Index

The numerical investigation of laminar natural convection of viscoplastic fluid in a two dimensional square enclosure has been reported in this work. The enclosed fluid is subjected to partial bi-heating from the bottom wall and symmetrical cooling from the sides under steady condition. Yield stress fluid has been heated through two heaters symmetrically placed on the either side of the centre of the bottom wall of the square enclosure. The viscoplastic fluid is the one which requires a minimum critical stress called yield stress to flow otherwise behave as a solid, have been modeled with Herschel–Bulkley model. Such fluids have significant technological relevance due to its wide application ranging from cosmetics products, food processing industries, pharmaceuticals to natural occurring like flow of debris and lava. The solution of governing partial differential equations has been approached using finite volume based formulation. Non uniform set of grid has been used. The effects of yield stress, heat flux, and power law index on the flow and thermal characteristics of the free convection of Herschel-Bulkley fluids have been studied for a particular value of Prandtl number. The flow and thermal fields have been investigated for the following ranges of conditions: Rayleigh number varies between 103 and 106 whereas power law index ranges from 0 to 1. The heat transfer characteristic has been depicted with the help of isotherms and the flow field has been illustrated by streamlines. The onset of convection is substantially delayed due to presence of yield stress of the fluid. This results in enhanced critical Rayleigh number for onset of convection. With increase in the Yield number in turn yield stress, results in the weakening of heat transfer through convection and at a particular relatively higher value of Yield number the heat transfer is solely taken place by conduction mode. Due to the symmetry in both heating and boundary conditions, the obtained isotherms and streamlines of the right half are symmetrical to the left half of the square enclosure. The conductive mode of heat transfer becomes dominated by increasing yield stress and reducing Ra and vice versa. The simultaneous presence of yielded and unyielded region presents an interesting pattern in the convection zone. Furthermore, it can be seen that rise in heat flux, in turn Ra, promotes the buoyancy driven circulation of viscoplastic fluid i.e. enhances natural convective heat transfer. In addition, the effect of power law index has been investigated. Power law index has little effect on thermal distribution and flow field.

scholarly journals Jet Impingement Heat Transfer of Confined Single and Double Jets with Non-Newtonian Power Law Nanofluid under the Inclined Magnetic Field Effects for a Partly Curved Heated Wall

2021 ◽  
Vol 13 (9) ◽  
pp. 5086
Author(s):  
Fatih Selimefendigil ◽  
Hakan F. Oztop ◽  
Ali J. Chamkha
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Particle Size ◽  
Aspect Ratio ◽  
Power Law ◽  
Volume Fraction ◽  
Inclined Magnetic Field ◽  
Magnetic Field Effects ◽  
Power Law Nanofluid ◽  
Power Law Index

Single and double impinging jets heat transfer of non-Newtonian power law nanofluid on a partly curved surface under the inclined magnetic field effects is analyzed with finite element method. The numerical work is performed for various values of Reynolds number (Re, between 100 and 300), Hartmann number (Ha, between 0 and 10), magnetic field inclination (γ, between 0 and 90), curved wall aspect ratio (AR, between 01. and 1.2), power law index (n, between 0.8 and 1.2), nanoparticle volume fraction (ϕ, between 0 and 0.04) and particle size in nm (dp, between 20 and 80). The amount of rise in average Nusselt (Nu) number with Re number depends upon the power law index while the discrepancy between the Newtonian fluid case becomes higher with higher values of power law indices. As compared to case with n = 1, discrepancy in the average Nu number are obtained as −38% and 71.5% for cases with n = 0.8 and n = 1.2. The magnetic field strength and inclination can be used to control the size and number or vortices. As magnetic field is imposed at the higher strength, the average Nu reduces by about 26.6% and 7.5% for single and double jets with n greater than 1 while it increases by about 4.78% and 12.58% with n less than 1. The inclination of magnetic field also plays an important role on the amount of enhancement in the average Nu number for different n values. The aspect ratio of the curved wall affects the flow field slightly while the average Nu variation becomes 5%. Average Nu number increases with higher solid particle volume fraction and with smaller particle size. At the highest particle size, it is increased by about 14%. There is 7% variation in the average Nu number when cases with lowest and highest particle size are compared. Finally, convective heat transfer performance modeling with four inputs and one output is successfully obtained by using Adaptive Neuro-Fuzzy Interface System (ANFIS) which provides fast and accurate prediction results.

scholarly journals Impact of autocatalytic chemical reaction in an Ostwald-de-Waele nanofluid flow past a rotating disk with heterogeneous catalysis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bai Yu ◽  
Muhammad Ramzan ◽  
Saima Riasat ◽  
Seifedine Kadry ◽  
Yu-Ming Chu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Differential Equations ◽  
Chemical Reaction ◽  
Power Law ◽  
Variable Thickness ◽  
Rotating Disk ◽  
Thermal Profile ◽  
Nanofluid Flow ◽  
Power Law Index

AbstractThe nanofluids owing to their alluring attributes like enhanced thermal conductivity and better heat transfer characteristics have a vast variety of applications ranging from space technology to nuclear reactors etc. The present study highlights the Ostwald-de-Waele nanofluid flow past a rotating disk of variable thickness in a porous medium with a melting heat transfer phenomenon. The surface catalyzed reaction is added to the homogeneous-heterogeneous reaction that triggers the rate of the chemical reaction. The added feature of the variable thermal conductivity and the viscosity instead of their constant values also boosts the novelty of the undertaken problem. The modeled problem is erected in the form of a system of partial differential equations. Engaging similarity transformation, the set of ordinary differential equations are obtained. The coupled equations are numerically solved by using the bvp4c built-in MATLAB function. The drag coefficient and Nusselt number are plotted for arising parameters. The results revealed that increasing surface catalyzed parameter causes a decline in thermal profile more efficiently. Further, the power-law index is more influential than the variable thickness disk index. The numerical results show that variations in dimensionless thickness coefficient do not make any effect. However, increasing power-law index causing an upsurge in radial, axial, tangential, velocities, and thermal profile.

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