Dipankar Choudhury

ANSYS · Research

Pressure based solvers in collocated grid arrangement require additional dissipation term in order to prevent pressure-velocity decoupling. Typically the dissipation is added through an interpolation procedure for the face velocity. While the face velocity interpolation resolves problems related to odd-even decoupling, the resulting dissipation is...

A cell centered high resolution scheme with the dissipation term based on dominant wave approach is examined here. A simpli�ed dominant eigenvalue expression based on the momentum equations together with low Mach number precondtioning is introduced. The dominant wave scheme was implemented in the unstructured cell centered framework capable of supp...

This paper traces the development of Computational Fluid Dynamics (CFD), from its beginnings in the second half of the 20th Century to the present time with special emphasis on the evolution of the market for commercial codes. A discussion is provided on the reasons behind the current ‘success’ of commercial CFD packages and the present issues conc...

In this paper, we use flow feature extraction to study a CFD application from the turbomachinery industry. We show that for this RANS, nearly incompressible simulation, our new eigen helicity density scheme outperforms the widely accepted λ2 scheme in identifying vortex regions. A new vortex coreline extraction algorithm is introduced, which extrac...

Turbulence initiated by Richtmyer-Meshkov (RM) instability provides an important environment for studying three-dimensional, high-speed, compressible, and variable-density flow physics. The active baroclinic term in the vorticity evolution equation complicates the vortex dynamics and challenges existing vortex identification schemes. In this paper,...

A variety of engineering applications involve incompressible flows in devices for which boundary pressures are known. The purpose of this article is to present a mathematical formulation and a computational method for the prediction of incompressible flow in domains with specified pressure boundaries. The computational treatment of specified pressu...

The present paper is primarily concerned with practical aspects of modeling complex turbulent flows. The issues of meshing and discretization, which are prerequisite to successful prediction of complex turbulent flows, are discussed. Near-wall treatments are briefly reviewed with the main focus on the wall function approach in view of its practical...

Flows in many engineering applications occur in devices that exhibit geometric periodicity, giving rise to flow characteristics that art spatially periodic. This periodicity can be of two types, translational and rotational. Since the geometries encountered in practice are often complex, periodic boundary-fitted grids art used over a typical module...

This paper proposes a simple near-wall treatment for practical use in calculations of complex wall-bounded turbulent flows. Being a natural extension of Launder and Spalding's standard wall functions [1], the proposed near-wall treatment employs two-layer wall functions [2] sensitized to pressure gradient. The new near-wall treatment is applied to...

Numerical solutions of Reynolds-Averaged Navier-Stokes equations are presented for the fluid flow and heat transfer over a backward-facing step, a benchmark test case for the 1994 ASME Winter Annual Meeting. Computations are carried out using FLUENT, a general-purpose CFD software package. A k-ε model based on the Renormalization Group (RNG) method...

Transport processes in most engineering applications occur in complex geometries. A control volume method is presented, based on generalized nonorthogonal curvilinear coordinates for the prediction of incompressible flow and related transport processes in complex geometries, The primitive variable formulation is adopted and a staggered grid, with c...

Natural convection is often employed due to its simplicity and reliability in the cooling of electronic equipment operating at low heat fluxes. In closely packed arrays of circuit boards containing evenly spaced heated components, the buoyancy-induced flow becomes periodically fully developed rather quickly. The dependence of the characteristics of...

Axial flow and heat transfer in a horizontal cylindrical annulus can be influenced by eccentricity of the inner cylinder and the presence of buoyancy forces. A numerical study is presented for the combined forced and free convection for the fully developed flow and heat transfer for eccentric annuli of different eccentricities and radius ratios. Th...

Physical situations where heat transfer occurs between materials with differing properties are commonly encountered in engineering practice, and often the geometries of interest are irregular. A method is proposed for discretization of the conductive heal fluxes for nonorthogonal coordinates, which accounts for the possible discontinuities in the t...

Two three-dimensional cabin airflow configurations have been the subject of experimental and analytical testing to establish the validity and role of computational fluid dynamics (CFD) tools in the design of cabin airflow distribution systems. The CFD tools considered here are two separate Navier-Stokes computer codes which have been used for a num...

Fluid-flow and heat-transfer results for a curved rectangular-duct model of a thermally developed laminar flow in the interfin passage of fine-pitched helically finned heat exchangers are presented. The study is restricted to fully developed velocity and temperature fields and carried out for values of the Dean number of up to 800 and Prandtl numbe...

An analysis is presented for fluid flow and heat transfer in a parallel plate channel with periodically spaced dimples. The flow is assumed to be constant property, two dimensional and laminar, with uniform wall temperature thermal boundary condition in the periodic fully developed region. A control-volume finite-difference method based on generali...

A control volume finite difference method based on general curvilinear coordinates was developed to predict fully developed flow and heat transfer in streamwise-periodic complex geometries. The method was used to predict velocity and temperature fields and overall quantities like friction factor and heat transfer coefficents for a parallel platecha...

An analysis is made of the combined forced and free convection for laminar flow in the entrance region of isothermal, inclined tubes. This involves the numerical calculation of the developing flow with significant buoyancy effects. Three independent parameters are introduced: the Prandtl number Pr, a modified Rayleigh number Ra*, and Ω, a paramete...

A new computational scheme was developed for predicting 3D flow and temperature fields in heat-exchanger passages. This approach uses a quasi-three-dimensional gap-integrated form of the governing equations. These equations can be applied many situations in which two dimensions of the computational domain are relatively large compared to the third...

The 14 papers contained in this volume are related to heat transfer in combustion systems and mathematical models of heat transfer. Fuels mentioned include natural gas, wood, coal, ethanol, and hazardous wastes. Several papers relate to combustion synthesis of materials and heat transfer in ceramic burners. Most of the papers have been processed se...

An experimental study has been conducted to ascertain the effects of introducing fiber bed absorbers on Trombe wall passive solar collectors. Two identical, Trombe wall passive solar units were constructed that incorporate the basic components of masonry collector-storage walls: glazings, masonry and thermal insulation. Both units were extensively...