The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
Shijun Liao - One of the best experts on this subject based on the ideXlab platform.
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A uniformly valid analytic solution of two-dimensional viscous flow over a Semi-Infinite Flat Plate
Journal of Fluid Mechanics, 1999Co-Authors: Shijun LiaoAbstract:We apply a new kind of analytic technique, namely the homotopy analysis method (HAM), to give an explicit, totally analytic, uniformly valid solution of the two-dimensional laminar viscous flow over a Semi-Infinite Flat Plate governed by f ‴(η)+α f (η) f ″(η)+β[1− f ′ 2 (η)]=0 under the boundary conditions f (0)= f ′(0)=0, f ′(+∞)=1. This analytic solution is uniformly valid in the whole region 0[les ]η
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a uniformly valid analytic solution of two dimensional viscous flow over a semi infinite Flat Plate
Journal of Fluid Mechanics, 1999Co-Authors: Shijun LiaoAbstract:We apply a new kind of analytic technique, namely the homotopy analysis method (HAM), to give an explicit, totally analytic, uniformly valid solution of the two-dimensional laminar viscous flow over a Semi-Infinite Flat Plate governed by f ‴(η)+α f (η) f ″(η)+β[1− f ′ 2 (η)]=0 under the boundary conditions f (0)= f ′(0)=0, f ′(+∞)=1. This analytic solution is uniformly valid in the whole region 0[les ]η<+∞. For Blasius' (1908) flow (α=1/2, β=0), this solution converges to Howarth's (1938) numerical result and gives a purely analytic value f ″(0)=0.332057. For the Falkner–Skan (1931) flow (α=1), it gives the same family of solutions as Hartree's (1937) numerical results and a related analytic formula for f ″(0) when 2[ges ]β[ges ]0. Also, this analytic solution proves that when −0.1988[les ]β0 Hartree's (1937) family of solutions indeed possess the property that f ′→1 exponentially as η→+∞. This verifies the validity of the homotopy analysis method and shows the potential possibility of applying it to some unsolved viscous flow problems in fluid mechanics.
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an explicit totally analytic solution of laminar viscous flow over a semi infinite Flat Plate
Communications in Nonlinear Science and Numerical Simulation, 1998Co-Authors: Shijun LiaoAbstract:Abstract In this paper, a new kind of analytic technique for nonlinear problems, namely the Homotopy Analysis Method, is applied to give an explicit, totally analytic solution of the Blasius' flow, i.e. the two dimensional (2D) laminar viscous flow over a Semi-Infinite Flat Plate. This analytic solution is valid in the whole region having physical meanings. To our knowledge, it is the first time in history that such a kind of explicit, totally analytic solution is given. This fact well verifies the great potential and validity of the Homotopy Analysis Method as a kind of powerful analytic tool for nonlinear problems in science and engineering.
Renato Tognaccini - One of the best experts on this subject based on the ideXlab platform.
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The start-up vortex issuing from a Semi-Infinite Flat Plate
Journal of Fluid Mechanics, 2002Co-Authors: P. Luchini, Renato TognacciniAbstract:The subject of the present work is the start-up vortex issuing from a sharp trailing edge accelerated from rest in still air. A numerical simulation of the flow has been performed in the case of a Semi-Infinite at Plate by solving the Navier–Stokes equations in the ψ_ω formulation. The numerical algorithm is based on a fast multigrid implicit integration of the difference equations in an unstructured mesh that is dynamically built to minimize the computational costs. A local refinement of the mesh near the edge of the Plate increases the accuracy of the simulation. The results show that the asymptotic stage of the vortex evolution is self-similar in the mean, but the appearance of instabilities produces a time-dependent flow which is not instantaneously self-similar.
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Coupling of conduction and convection past an impulsively started Semi-Infinite Flat Plate
International Journal of Heat and Mass Transfer, 2000Co-Authors: A. Pozzi, Renato TognacciniAbstract:Abstract A quasi-analytical solution of the conjugated heat transfer problem for a Semi-Infinite Flat Plate that is impulsively accelerated in a compressible laminar flow with Prandtl number equal to 1 is proposed. The solution is based on an integral formulation both for the momentum and energy equations in the fluid and for the thermal coupling between the fluid and the solid. The results are compared to previously obtained exact solutions in the limiting conditions of ‘asymptotic’ and ‘steady’ flow. The influence on the temperature field of the main parameters characterizing the problem is discussed.
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Comparison of viscous and inviscid numerical simulations of the start-up vortex issuing from a Semi-Infinite Flat Plate
ESAIM: Proceedings, 1999Co-Authors: P. Luchini, Renato TognacciniAbstract:Subject of the present work is the start-up vortex issuing from a sharp trailing edge accelerated from rest in still air. A numerical simulation of the flow has been performed in case of a Semi-Infinite Flat Plate by solving the Navier-Stokes equations in the Psi-Omega formulation. The new numerical algorithm is based on a fast multigrid implicit integration of the difference equations in an unstructured mesh that is dynamically built to minimize the computational costs. The results, compared with inviscid lumped-vortex simulations, show the appearance of instabilities that quickly destroy the regular structure of the spiral vortex. This analysis gives a contribution to the understanding of a physical problem still discussed in the literature and raises the question whether the application of numerical regularization procedures can tend to stabilize a phenomenon even when its physical nature is unstable.
G Nath - One of the best experts on this subject based on the ideXlab platform.
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unsteady flow and heat transfer on a semi infinite Flat Plate with an aligned magnetic field
International Journal of Engineering Science, 1999Co-Authors: Harmindar S Takhar, Ali J. Chamkha, G NathAbstract:The unsteady laminar boundary layer flow of an electrically conducting fluid past a Semi-Infinite Flat Plate with an aligned magnetic field has been studied when at time t > 0 the Plate is impulsively moved with a constant velocity which is in the same or opposite direction to that of free stream velocity. The effect of the induced magnetic field has been included in the analysis. The non-linear partial differential equations have been solved numerically using an implicit finite-difference method. The effect of the impulsive motion of the surface is found to be more pronounced on the skin friction but its effect on the x-component of the induced magnetic field and heat transfer is small. Velocity defect occurs near the surface when the Plate is impulsively moved in the same direction as that of the free stream velocity. The surface shear stress, x-component of the induced magnetic field on the surface and the surface heat transfer decrease with an increasing magnetic field, but they increase with the reciprocal of the magnetic Prandtl number. However, the effect of the reciprocal of the magnetic Prandtl number is more pronounced on the x-component of the induced magnetic field. (C) 1999 Elsevier Science Ltd. All rights reserved.
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Conjugate MHD flow past a Flat Plate
Acta Mechanica, 1994Co-Authors: I. Pop, Mahesh Kumari, G NathAbstract:A boundary layer solution for the conjugate forced convection flow of an electrically conducting fluid over a Semi-Infinite Flat Plate in the presence of a transverse magnetic field is presented. The governing nonsimilar partial differential equations are solved numerically using the Keller box method. Values of the temperature profiles of the Plate are obtained for various values of the parameters entering the problem and are given in a table and shown on graphs.
P. Luchini - One of the best experts on this subject based on the ideXlab platform.
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The start-up vortex issuing from a Semi-Infinite Flat Plate
Journal of Fluid Mechanics, 2002Co-Authors: P. Luchini, Renato TognacciniAbstract:The subject of the present work is the start-up vortex issuing from a sharp trailing edge accelerated from rest in still air. A numerical simulation of the flow has been performed in the case of a Semi-Infinite at Plate by solving the Navier–Stokes equations in the ψ_ω formulation. The numerical algorithm is based on a fast multigrid implicit integration of the difference equations in an unstructured mesh that is dynamically built to minimize the computational costs. A local refinement of the mesh near the edge of the Plate increases the accuracy of the simulation. The results show that the asymptotic stage of the vortex evolution is self-similar in the mean, but the appearance of instabilities produces a time-dependent flow which is not instantaneously self-similar.
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Comparison of viscous and inviscid numerical simulations of the start-up vortex issuing from a Semi-Infinite Flat Plate
ESAIM: Proceedings, 1999Co-Authors: P. Luchini, Renato TognacciniAbstract:Subject of the present work is the start-up vortex issuing from a sharp trailing edge accelerated from rest in still air. A numerical simulation of the flow has been performed in case of a Semi-Infinite Flat Plate by solving the Navier-Stokes equations in the Psi-Omega formulation. The new numerical algorithm is based on a fast multigrid implicit integration of the difference equations in an unstructured mesh that is dynamically built to minimize the computational costs. The results, compared with inviscid lumped-vortex simulations, show the appearance of instabilities that quickly destroy the regular structure of the spiral vortex. This analysis gives a contribution to the understanding of a physical problem still discussed in the literature and raises the question whether the application of numerical regularization procedures can tend to stabilize a phenomenon even when its physical nature is unstable.
Vasilis Sassanis - One of the best experts on this subject based on the ideXlab platform.
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sound radiated by the interaction of non homogeneous turbulence on a transversely sheared flow with leading and trailing edges of semi infinite Flat Plate
Bulletin of the American Physical Society, 2017Co-Authors: Mohammed Afsar, Vasilis SassanisAbstract:The small amplitude unsteady motion on a transversely sheared mean flow is determined by two arbitrary convected quantities with a particular choice of gauge in which the Fourier transform of the pressure is linearly-related to a scalar potential whose integral solution can be written in terms of one of these convected quantities. This formulation becomes very useful for studying Rapid-distortion theory problems involving solid surface interaction. Recent work by Goldstein et al. (JFM, 2017) has shown that the convected quantities are related to the turbulence by exact conservation laws, which allow the upstream boundary conditions for interaction of a turbulent shear flow with a solid-surface (for example) to be derived self-consistently with appropriate asymptotic separation of scales. This result requires the imposition of causality on an intermediate variable within the conservation laws that represents the local particle displacement. In this talk, we use the model derived in Goldstein et al. for trailing edge noise and compare it to leading edge noise on a Semi-Infinite Flat Plate positioned parallel to the level curves of the mean flow. Since the latter represents the leading order solution for the aerofoil interaction problem, these results are expected to be generic.
