Axisymmetric Flow and Heat Transfer on a Moving Cylinder

2021 ◽  
pp. 185-202
Author(s):  
Vasile Marinca ◽  
Nicolae Herisanu ◽  
Bogdan Marinca
Keyword(s):  
Heat Transfer ◽  
Axisymmetric Flow ◽  
Flow And Heat Transfer ◽  
Moving Cylinder

scholarly journals Construction of Analytic Solution to Axisymmetric Flow and Heat Transfer on a Moving Cylinder

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1335
Author(s):  
Vasile Marinca ◽  
Nicolae Herisanu
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Stokes Equations ◽  
Nonlinear Differential Equations ◽  
Axisymmetric Flow ◽  
Control Parameters ◽  
Auxiliary Functions ◽  
Flow And Heat Transfer ◽  
Moving Cylinder ◽  
Convergence Control

Based on a new kind of analytical approach, namely the Optimal Auxiliary Functions Method (OAFM), a new analytical procedure is proposed to solve the problem of the annular axisymmetric stagnation flow and heat transfer on a moving cylinder with finite radius. As a novelty, explicit analytical solutions were obtained for the considered complex problem. First, the Navier–Stokes equations were simplified by means of similarity transformations that depended on different parameters and some combinations of these parameters, and the problem under study was reduced to six nonlinear ordinary differential equations with six unknowns. The OAFM proves to be a powerful tool for finding an accurate analytical solution for nonlinear problems, ensuring a fast convergence after the first iteration, even if the small or large parameters are absent, since the determination of the convergence-control parameters is independent of the magnitude of the coefficients that appear in the nonlinear differential equations. Concerning the main novelties of the proposed approach, it is worth mentioning the presence of some auxiliary functions, the involvement of the convergence-control parameters, the construction of the first iteration and much freedom to select the procedure for determining the optimal values of the convergence-control parameters.

scholarly journals Viscous flow over a stretching (shrinking) and porous cylinder of non-uniform radius

2019 ◽  
Vol 11 (9) ◽  
pp. 168781401987984
Author(s):  
Azhar Ali ◽  
Dil Nawaz Khan Marwat ◽  
Saleem Asghar
Keyword(s):  
Heat Transfer ◽  
Current Model ◽  
Axisymmetric Flow ◽  
Complex Problem ◽  
Skin Friction Coefficient ◽  
Porous Cylinder ◽  
Heated Cylinder ◽  
Flow And Heat Transfer ◽  
Uniform Diameter ◽  
Benchmark Solutions

The classical models of viscous flows and heat transfer are reformulated in this article. The physical problem describes flow and heat transfer over a stretching (shrinking) and porous cylinder of non-uniform radius. The mathematical model is presented in the form of new equations and dimensionless parameters by means of reframing techniques. A porous and heated cylinder of a non-uniform diameter is stretched (shrunk) with variable stretching (shrinking) velocities. The governing equations and their physical geometrical perspectives are summarized into simplest boundary value ordinary differential equations. A set of unseen, generalized, and convenient transformations are used to solve the complex problem. The current formulation accumulates all the previous models of axisymmetric flow and heat transfer toward stretching (shrinking) and porous cylinder presented in the literature and prevails over all such models. The current model can be easily transformed into classical simulations for particular values of the parameters. The problem is solved numerically and the results were compared with the benchmark solutions. Velocity, temperature, skin friction coefficient, and Nusselt number profiles are plotted and analyzed for different values of the parameters. Moreover, coupling effects of all parameters are seen on flow and heat transfer characteristics and new results are explored and discussed.

Axisymmetric Stagnation-Point Flow and Heat Transfer of a Viscous Fluid on a Moving Cylinder With Time-Dependent Axial Velocity and Uniform Transpiration

2004 ◽  
Vol 126 (6) ◽  
pp. 997-1005 ◽  
Author(s):  
R. Saleh ◽  
A. B. Rahimi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Axial Velocity ◽  
Time Dependent ◽  
Navier Stokes ◽  
Flow And Heat Transfer ◽  
Moving Cylinder ◽  
Self Similar ◽  
Suction Rate ◽  
Axial Speed

The unsteady viscous flow and heat transfer in the vicinity of an axisymmetric stagnation point of an infinite moving cylinder with time-dependent axial velocity and with uniform normal transpiration Uo are investigated. The impinging free stream is steady and with a constant strain rate k¯. An exact solution of the Navier–Stokes equations and energy equation is derived in this problem. A reduction of these equations is obtained by use of appropriate transformations for the most general case when the transpiration rate is also time-dependent but results are presented only for uniform values of this quantity. The general self-similar solution is obtained when the axial velocity of the cylinder and its wall temperature or its wall heat flux vary as specified time-dependent functions. In particular, the cylinder may move with constant speed, with exponentially increasing–decreasing axial velocity, with harmonically varying axial speed, or with accelerating–decelerating oscillatory axial speed. For self-similar flow, the surface temperature or its surface heat flux must have the same types of behavior as the cylinder motion. For completeness, sample semisimilar solutions of the unsteady Navier–Stokes and energy equations have been obtained numerically using a finite-difference scheme. Some of these solutions are presented for special cases when the time-dependent axial velocity of the cylinder is a step-function, and a ramp function. All the solutions above are presented for Reynolds numbers, Re=ka¯2/2υ, ranging from 0.1 to 100 for different values of dimensionless transpiration rate, S=Uo/ka¯, where a is cylinder radius and υ is kinematic viscosity of the fluid. Absolute value of the shear-stresses corresponding to all the cases increase with the increase of Reynolds number and suction rate. The maximum value of the shear- stress increases with increasing oscillation frequency and amplitude. An interesting result is obtained in which a cylinder moving with certain exponential axial velocity function at any particular value of Reynolds number and suction rate is axially stress-free. The heat transfer coefficient increases with the increasing suction rate, Reynolds number, Prandtl number, oscillation frequency and amplitude. Interesting means of cooling and heating processes of cylinder surface are obtained using different rates of transpiration. It is shown that a cylinder with certain type of exponential wall temperature exposed to a temperature difference has no heat transfer.

Direct Numerical Simulation of Flow and Heat Transfer From a Sphere in a Uniform Cross-Flow

2000 ◽  
Vol 123 (2) ◽  
pp. 347-358 ◽  
Author(s):  
P. Bagchi ◽  
M. Y. Ha ◽  
S. Balachandar
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Vortex Shedding ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Temperature Fields ◽  
Flow And Heat Transfer

Direct numerical solution for flow and heat transfer past a sphere in a uniform flow is obtained using an accurate and efficient Fourier-Chebyshev spectral collocation method for Reynolds numbers up to 500. We investigate the flow and temperature fields over a range of Reynolds numbers, showing steady and axisymmetric flow when the Reynolds number is less than 210, steady and nonaxisymmetric flow without vortex shedding when the Reynolds number is between 210 and 270, and unsteady three-dimensional flow with vortex shedding when the Reynolds number is above 270. Results from three-dimensional simulation are compared with the corresponding axisymmetric simulations for Re>210 in order to see the effect of unsteadiness and three-dimensionality on heat transfer past a sphere. The local Nusselt number distribution obtained from the 3D simulation shows big differences in the wake region compared with axisymmetric one, when there exists strong vortex shedding in the wake. But the differences in surface-average Nusselt number between axisymmetric and three-dimensional simulations are small owing to the smaller surface area associated with the base region. The shedding process is observed to be dominantly one-sided and as a result axisymmetry of the surface heat transfer is broken even after a time-average. The one-sided shedding also results in a time-averaged mean lift force on the sphere.

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