The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
J B L M Campos - One of the best experts on this subject based on the ideXlab platform.
-
mass transport regimes in a laminar boundary layer with suction parallel flow and high Peclet Number
International Journal of Heat and Mass Transfer, 2004Co-Authors: J M Miranda, J B L M CamposAbstract:Abstract Mass transport in a boundary layer with suction was studied for a parallel flow, laminar regime and high Peclet Number. Mass transport mechanisms involved were analyzed and the respective mass transport fluxes were quantified by numerical methods. According to the magnitude of the convective fluxes, mass transport regimes were established. A simple, but accurate equation was deduced to identify the dominant convective flux and the transport regime. This identification only requires measurable variables combined in dimensionless groups. The accuracy of the equation was proved through the numerical solution of the governing flow and mass transport equations. The concentration field inside the mass boundary layer and the concentration polarization level at the permeable surface are intrinsically related with the dominant convective flux. A simple equation was deduced relating the concentration polarization level at the permeable surface and the parameter Ω j z , which characterizes the transport regime.
-
Mass transport regimes in a laminar boundary layer with suction––parallel flow and high Peclet Number
International Journal of Heat and Mass Transfer, 2004Co-Authors: J M Miranda, J B L M CamposAbstract:Abstract Mass transport in a boundary layer with suction was studied for a parallel flow, laminar regime and high Peclet Number. Mass transport mechanisms involved were analyzed and the respective mass transport fluxes were quantified by numerical methods. According to the magnitude of the convective fluxes, mass transport regimes were established. A simple, but accurate equation was deduced to identify the dominant convective flux and the transport regime. This identification only requires measurable variables combined in dimensionless groups. The accuracy of the equation was proved through the numerical solution of the governing flow and mass transport equations. The concentration field inside the mass boundary layer and the concentration polarization level at the permeable surface are intrinsically related with the dominant convective flux. A simple equation was deduced relating the concentration polarization level at the permeable surface and the parameter Ω j z , which characterizes the transport regime.
Xuehong Wu - One of the best experts on this subject based on the ideXlab platform.
-
a two level variational multiscale meshless local petrov galerkin vms mlpg method for convection diffusion problems with large Peclet Number
Computers & Fluids, 2017Co-Authors: Zhengji Chen, Zengyao Li, Xuehong WuAbstract:Abstract It is challengeable to obtain the stable and accurate solutions of convection-diffusion problems with large Peclet Number ( Pe ) since the convection term may cause oscillation solutions at large Pe . In this paper, a unit operator (first level) and an orthogonal project operator (second level) are constructed to act as the stability terms for meshless local Petrov-Galerkin (MLPG) method, which is called a two-level variational multiscale MLPG (VMS-MLPG) method. The VMS-MLPG method is applied to eliminate oscillation, overshoots and undershoots of MLPG method at large Pe . The prediction accuracy and the numerical stability of the proposed method for the Smith-Hutton and the Brezzi problems are analyzed and validated by comparing with the MLPG method and the finite volume method (FVM) with various difference schemes. It is showed that the present VMS-MLPG method can guarantee the stable and reasonable solutions of convection-diffusion problems with large Peclet Number.
-
A two-level variational multiscale meshless local Petrov–Galerkin (VMS-MLPG) method for convection-diffusion problems with large Peclet Number
Computers & Fluids, 2017Co-Authors: Zhengji Chen, Zengyao Li, Xuehong WuAbstract:Abstract It is challengeable to obtain the stable and accurate solutions of convection-diffusion problems with large Peclet Number ( Pe ) since the convection term may cause oscillation solutions at large Pe . In this paper, a unit operator (first level) and an orthogonal project operator (second level) are constructed to act as the stability terms for meshless local Petrov-Galerkin (MLPG) method, which is called a two-level variational multiscale MLPG (VMS-MLPG) method. The VMS-MLPG method is applied to eliminate oscillation, overshoots and undershoots of MLPG method at large Pe . The prediction accuracy and the numerical stability of the proposed method for the Smith-Hutton and the Brezzi problems are analyzed and validated by comparing with the MLPG method and the finite volume method (FVM) with various difference schemes. It is showed that the present VMS-MLPG method can guarantee the stable and reasonable solutions of convection-diffusion problems with large Peclet Number.
Zhengji Chen - One of the best experts on this subject based on the ideXlab platform.
-
a new stability parameter in streamline upwind meshless petrov galerkin method for convection diffusion problems at large Peclet Number
Numerical Heat Transfer Part B-fundamentals, 2019Co-Authors: Zhengji Chen, Zengyao LiAbstract:AbstractThe numerical oscillation will occur in convection–diffusion equations as special linear problems at large Peclet Number (Pe) in the numerical calculation process. In this article, we propose a new definition of the stability parameter in streamline upwind meshless Petrov–Galerkin (SUMLPG) method. The most important feature of the proposed method is that the test function in the stabilization term is taken into the differential operator-like form v*=v+τLadvv. The stability parameter τ is designed to adjust the convection strength to achieve accurate and stable numerical solutions. Several classical examples are adopted to assessment the accuracy and stability of the proposed stability parameter. It is proven that the proposed method is especially suitable for convection–diffusion problems with large Pe.
-
a two level variational multiscale meshless local petrov galerkin vms mlpg method for convection diffusion problems with large Peclet Number
Computers & Fluids, 2017Co-Authors: Zhengji Chen, Zengyao Li, Xuehong WuAbstract:Abstract It is challengeable to obtain the stable and accurate solutions of convection-diffusion problems with large Peclet Number ( Pe ) since the convection term may cause oscillation solutions at large Pe . In this paper, a unit operator (first level) and an orthogonal project operator (second level) are constructed to act as the stability terms for meshless local Petrov-Galerkin (MLPG) method, which is called a two-level variational multiscale MLPG (VMS-MLPG) method. The VMS-MLPG method is applied to eliminate oscillation, overshoots and undershoots of MLPG method at large Pe . The prediction accuracy and the numerical stability of the proposed method for the Smith-Hutton and the Brezzi problems are analyzed and validated by comparing with the MLPG method and the finite volume method (FVM) with various difference schemes. It is showed that the present VMS-MLPG method can guarantee the stable and reasonable solutions of convection-diffusion problems with large Peclet Number.
-
A two-level variational multiscale meshless local Petrov–Galerkin (VMS-MLPG) method for convection-diffusion problems with large Peclet Number
Computers & Fluids, 2017Co-Authors: Zhengji Chen, Zengyao Li, Xuehong WuAbstract:Abstract It is challengeable to obtain the stable and accurate solutions of convection-diffusion problems with large Peclet Number ( Pe ) since the convection term may cause oscillation solutions at large Pe . In this paper, a unit operator (first level) and an orthogonal project operator (second level) are constructed to act as the stability terms for meshless local Petrov-Galerkin (MLPG) method, which is called a two-level variational multiscale MLPG (VMS-MLPG) method. The VMS-MLPG method is applied to eliminate oscillation, overshoots and undershoots of MLPG method at large Pe . The prediction accuracy and the numerical stability of the proposed method for the Smith-Hutton and the Brezzi problems are analyzed and validated by comparing with the MLPG method and the finite volume method (FVM) with various difference schemes. It is showed that the present VMS-MLPG method can guarantee the stable and reasonable solutions of convection-diffusion problems with large Peclet Number.
Mushtaq Ahmed - One of the best experts on this subject based on the ideXlab platform.
-
On Two-Dimensional Variable Viscosity Fluid Motion with Body Forcefor Intermediate Peclet Number Via von-Mises Coordinates
International Journal of Fluid Mechanics & Thermal Sciences, 2019Co-Authors: Mushtaq AhmedAbstract:This article uses von-Mises coordinates to present a class of new exact solutions of the system of partial differential equations for the plane steady motion of incompressible fluid of variable viscosity in presence of body forcefor moderate Peclet Number. This communication applies successive transformation technique and characterizes streamlines through an equation relating a differentiable function f(x) and a function of stream function. Considering the function of stream function satisfies a specific relation, the exact solutions for moderate Peclet Number with body force are determined for given one component of the body force when f(x) takes a specific value and when it is not. In both the cases, it shows an infinite set of streamlines, the velocity components, viscosity function, generalized energy function and temperature distribution for intermediate Peclet Number in presence of body force. When f(x) takes a specific value, a relation between viscosity and temperature function is observed.
-
On Plane Motion of Incompressible Variable Viscosity Fluids with Moderate Peclet Number in Presence of Body Force Via Von-Mises Coordinates
International Journal of Fluid Mechanics & Thermal Sciences, 2019Co-Authors: Mushtaq AhmedAbstract:The aim of this article is to use von-Mises coordinates to find a class of new exact solutionsof the equations governing the plane steady motion with moderate Peclet Number of incompressible fluid of variable viscosity in presence of body force. An equation relating a differentiable function and a stream function characterizes the class under consideration. When the differentiable function is parabolic and when it is not, in both the cases, it finds exact solutions for given one component of the body force. This discourse shows an infinite set of streamlines and the velocity components, viscosity function, generalized energy function and temperature distribution for moderate Peclet Number in presence of body force. Moreover, for parabolic case, it obtains viscosity as a function of temperature distribution for moderate Peclet Number.
-
A Class of Exact Solutions for a Variable Viscosity Flow with Body Force for Moderate Peclet Number ViaVon-Mises Coordinates
Food Microbiology, 2019Co-Authors: Mushtaq AhmedAbstract:The objective of this article is to communicate a class of new exact solutions of the plane equation of momentum with body force, energy and continuity for moderate Peclet Number in von-Mises coordinates. Viscosity of fluid is variable but its density and thermal conductivity are constant. The class characterizes the streamlines pattern through an equation relating two continuously differentiable functions and a function of stream function ψ. Applying the successive transformation technique, the basic equations are prepared for exact solutions. It finds exact solutions for class of flows for which the function of stream function varies linearly and exponentially. The linear case shows viscosity and temperature for moderate Peclet Number for two variety of velocity profile. The first velocity profile fixes both the functions of characteristic equation whereas the second keeps one of them arbitrary. The exponential case finds that the temperature distribution, due to heat generation, remains constant for all Peclet Numbers except at 4 where it follows a specific formula. There are streamlines, velocity components, viscosity and temperature distribution in presence of body force for a large Number of the finite Peclet Number.
-
A Class of New Exact Solution of Equations for Motion of Variable Viscosity Fluid in Presence of Body Force with Moderate Peclet Number
2019Co-Authors: Mushtaq AhmedAbstract:This is to communicate a class of new exact solutions of the equations governing the steady plane motion of fluid with constant density, constant thermal conductivity but variable viscosity and body force term to the right-hand side of Navier-Stokes equations with moderate Peclet Numbers. Exact solutions are obtained for Peclet Numbers between zero and infinity except 2, for given one component of the body force using successive transformation technique and a new characterization for the streamlines. A temperature distribution formula, due to heat generation, is obtained when Peclet Number is 4 other wise temperature distribution is found to be constant. The exact solutions are large in Number as streamlines, velocity components, viscosity function, and energy function and temperature distribution in presence of body force exists for a huge Number of the moderate Peclet Number.
Zengyao Li - One of the best experts on this subject based on the ideXlab platform.
-
a new stability parameter in streamline upwind meshless petrov galerkin method for convection diffusion problems at large Peclet Number
Numerical Heat Transfer Part B-fundamentals, 2019Co-Authors: Zhengji Chen, Zengyao LiAbstract:AbstractThe numerical oscillation will occur in convection–diffusion equations as special linear problems at large Peclet Number (Pe) in the numerical calculation process. In this article, we propose a new definition of the stability parameter in streamline upwind meshless Petrov–Galerkin (SUMLPG) method. The most important feature of the proposed method is that the test function in the stabilization term is taken into the differential operator-like form v*=v+τLadvv. The stability parameter τ is designed to adjust the convection strength to achieve accurate and stable numerical solutions. Several classical examples are adopted to assessment the accuracy and stability of the proposed stability parameter. It is proven that the proposed method is especially suitable for convection–diffusion problems with large Pe.
-
a two level variational multiscale meshless local petrov galerkin vms mlpg method for convection diffusion problems with large Peclet Number
Computers & Fluids, 2017Co-Authors: Zhengji Chen, Zengyao Li, Xuehong WuAbstract:Abstract It is challengeable to obtain the stable and accurate solutions of convection-diffusion problems with large Peclet Number ( Pe ) since the convection term may cause oscillation solutions at large Pe . In this paper, a unit operator (first level) and an orthogonal project operator (second level) are constructed to act as the stability terms for meshless local Petrov-Galerkin (MLPG) method, which is called a two-level variational multiscale MLPG (VMS-MLPG) method. The VMS-MLPG method is applied to eliminate oscillation, overshoots and undershoots of MLPG method at large Pe . The prediction accuracy and the numerical stability of the proposed method for the Smith-Hutton and the Brezzi problems are analyzed and validated by comparing with the MLPG method and the finite volume method (FVM) with various difference schemes. It is showed that the present VMS-MLPG method can guarantee the stable and reasonable solutions of convection-diffusion problems with large Peclet Number.
-
A two-level variational multiscale meshless local Petrov–Galerkin (VMS-MLPG) method for convection-diffusion problems with large Peclet Number
Computers & Fluids, 2017Co-Authors: Zhengji Chen, Zengyao Li, Xuehong WuAbstract:Abstract It is challengeable to obtain the stable and accurate solutions of convection-diffusion problems with large Peclet Number ( Pe ) since the convection term may cause oscillation solutions at large Pe . In this paper, a unit operator (first level) and an orthogonal project operator (second level) are constructed to act as the stability terms for meshless local Petrov-Galerkin (MLPG) method, which is called a two-level variational multiscale MLPG (VMS-MLPG) method. The VMS-MLPG method is applied to eliminate oscillation, overshoots and undershoots of MLPG method at large Pe . The prediction accuracy and the numerical stability of the proposed method for the Smith-Hutton and the Brezzi problems are analyzed and validated by comparing with the MLPG method and the finite volume method (FVM) with various difference schemes. It is showed that the present VMS-MLPG method can guarantee the stable and reasonable solutions of convection-diffusion problems with large Peclet Number.
