Suhas V. Patankar

Bio: Suhas V. Patankar is an academic researcher from University of Minnesota. The author has contributed to research in topics: Heat transfer & Turbulence. The author has an hindex of 42, co-authored 135 publications receiving 7165 citations. Previous affiliations of Suhas V. Patankar include Innovative Research Inc..

Laminar mixed convection in a horizontal semicircular duct with axially nonuniform thermal boundary condition on the flat wall

Abstract: Mixed convection in a horizontal semicircular duct is studied numerically. An axially nonuniform temperature distribution is prescribed on the flat wall, with the midsection at a higher temperature than the end sections. The full three-dimensional Navier-Stokes equations coupled with the energy equation are solved using a control-volume method. Results are presented for two values of the Grashof number (Gr = 5 [times] 10[sup 3] and 5 [times] 10[sup 4]) and three values of the Reynolds number (Re = 10, 20, 50), for a gas with Prandtl number of 0.7. For flow conditions characterized by a large value of the parameter Gr/R[sup 2], the buoyancy forces give rise to both longitudinal and transverse rolls in the duct, which cause nonuniformities in the heat flux distribution. The secondary flow pattern and the heat flux distribution on the heated section of the flat wall are strongly dependent on the thermal boundary condition on the curved wall of the duct.

Enhancements of the simple method for predicting incompressible fluid flows

Abstract: Variations of the SIMPLE method of Patankar and Spalding have been widely used over the past decade to obtain numerical solutions to problems involving incompressible flows. The present paper shows several modifications to the method which both simplify its implementation and reduce solution costs. The performances of SIMPLE, SIMPLER, and SIMPLEC (the present method) are compared for two recirculating flow problems. The paper is addressed to readers who already have experience with SIMPLE or its variants.

Numerical solution of saddle point problems

Abstract: Large linear systems of saddle point type arise in a wide variety of applications throughout computational science and engineering. Due to their indefiniteness and often poor spectral properties, such linear systems represent a significant challenge for solver developers. In recent years there has been a surge of interest in saddle point problems, and numerous solution techniques have been proposed for this type of system. The aim of this paper is to present and discuss a large selection of solution methods for linear systems in saddle point form, with an emphasis on iterative methods for large and sparse problems.

Error analysis and estimation for the finite volume method with applications to fluid flows

Abstract: The accuracy of numerical simulation algorithms is one of main concerns in modern Computational Fluid Dynamics. Development of new and more accurate mathematical models requires an insight into the problem of numerical errors. In order to construct an estimate of the solution error in Finite Volume calculations, it is first necessary to examine its sources. Discretisation errors can be divided into two groups: errors caused by the discretisation of the solution domain and equation discretisation errors. The first group includes insufficient mesh resolution, mesh skewness and non-orthogonality. In the case of the second order Finite Volume method, equation discretisation errors are represented through numerical diffusion. Numerical diffusion coefficients from the discretisation of the convection term and the temporal derivative are derived. In an attempt to reduce numerical diffusion from the convection term, a new stabilised and bounded second-order differencing scheme is proposed. Three new methods of error estimation are presented. The Direct Taylor Series Error estimate is based on the Taylor series truncation error analysis. It is set up to enable single-mesh single-run error estimation. The Moment Error estimate derives the solution error from the cell imbalance in higher moments of the solution. A suitable normalisation is used to estimate the error magnitude. The Residual Error estimate is based on the local inconsistency between face interpolation and volume integration. Extensions of the method to transient flows and the Local Residual Problem error estimate are also given. Finally, an automatic error-controlled adaptive mesh refinement algorithm is set up in order to automatically produce a solution of pre-determined accuracy. It uses mesh refinement and unrefinement to control the local error magnitude. The method is tested on several characteristic flow situations, ranging from incompressible to supersonic flows, for both steady-state and transient problems.