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..

Numerical method for the prediction of free surface flows in domains with moving boundaries

Abstract: Two-fluid flows in domains with moving boundaries are encountered in specialized engineering applications. The present study focuses on the development of a computational method far the prediction of such flows using a combination of moving grids and the volume-of-fluid technique. Moving grids are used to accommodate the motion of the domain boundaries. The volume-of-fluid technique is generalized to moving grids for tracking the motion of free surfaces between two fluids in deforming domains. The method allows one of the two fluids to be compressible. Discretization is carried out using a control-volume method, and explicit time stepping is used for temporal differencing. The proposed method, presented for regular coordinates in two dimensions, can be readily generalized to complex domains shapes using curvilinear coordinates and to three-dimensional analyses. The computational method is applied for the prediction of gas-liquid flows in a reciprocating compressor. Results illustrate that the proposed met...

Performance of a Multigrid Method with AN Improved Discretization Scheme for Three-Dimensional Fluid Flow Calculations

Abstract: This article reports the performance of the block-correction-based coupled multigrid method in conjunction with an improved discretization scheme for the solution of three-dimensional fluid flow problems. Laminar flow in a cubic cavity with a moving wall is calculated for different Reynolds numbers. The performance of the multigrid method is compared with that of a single-grid method based on the SIMPLER algorithm. To highlight the combined advantage of the improved discretization scheme and the multigrid method, the overall performance, in terms of CPU times for a prescribed accuracy, of the proposed calculation procedure is also compared with that of a conventional single-grid method based on the power-law differencing scheme and the SIMPLER algorithm.

Numerical analysis of water spray system in the entrance region of a two-dimensional channel using lagrangian approach

Abstract: A numerical study of a turbulent gas-liquid droplet flow is presented using the Lagrangian approach for the discrete phase and the Eulerian approach for the continuous phase. The spray nozzle is mounted on the wall of a two-dimensional plane channel, The influence of different directional angles as well as the angle of spray on the velocity and temperature field of the main phase are studied. Three sine categories are used to model the spray with the mean mass diameter of I mm, Two different spray angles are defined, namely 10° and 60°, The average directional angle varies (measured from the wall) from 60° to 120°.

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.