Siva Thangam

• Stevens Institute of Technology

Experimental and computational investigations of turbulent flow past projectiles is modeled as axial flow past a cylinder with a free-spinning base. A subsonic wind tunnel with a forward-sting mounted spinning cylinder is used for experiments. In addition, a free-jet facility is used for benchmarking the experimental set up. Experiments are perform...

This paper discusses the development of an effective electrolytic in‐process dressing technique for high speed grinding. An innovative foil electrode has been designed and tested. The performance of a hydrodynamic foil electrode is discussed. Experimental investigations confirm that foil electrodes show significant improvement on electrolytic in‐pr...

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Turbulent flow past spinning projectiles is considered both from a computational and experimental point of view. An anisotropic two-equation Reynolds-stress model that incorporates the effect of rotation-modified energy spectrum and swirl is used to represent flow past spinning projectiles of circular cross-section at zero angle of attack. Computat...

The fluid flow problem in a traditional electrolytic in-process dressing (ELID) system is analyzed and solved numerically. The predicted mean velocity profiles in the dressing zone show flow patterns that are in good agreement with the mean velocity distributions for plane laminar/turbulent Couette flows observed in the experiments. The computation...

An anisotropic two-equation Reynolds-stress model is developed by considering the modifications to the energy spectrum and through invariance based scaling. In this approach the effect of rotation is used to modify the energy spectrum, while the influence of swirl is modeled based on scaling laws. The resulting generalized model is validated for be...

A technique for the development of continuous models that are suitable for representing both the subgrid scale stresses in large eddy simulation and the Reynolds stresses in the Reynolds averaged Navier-Stokes formulation is described. A recursion approach is used to bridge the length scale disparity from the cut-off wavenumber to those in the ener...

The modeling of the flow about spinning cylindrical bodies in tandem has several important applications including the design of smart submunitions. The objective of this study was to examine the flow about a pair of spinning cylinders, estimate the drag, and explore methodologies to control their relative position during flight. To accomplish this...

An anisotropic turbulence model for the prediction of incompressible flows with curvature and swirl has been developed, implemented and validated. The model utilizes a phenomenological treatment of the energy spectrum to include the effects of rotation and swirl in turbulent flows. The resulting set of modeled form of transport equations for the tu...

A turbulence model for the prediction of incompressible flows in complex geometries in the presence of curvature and swirl is developed. The model utilizes a phenomenological treatment of the energy spectrum to include the contributions of rotation and swirl. The modeled form of the equations include an anisotropic Reynolds stress tensor representa...

Experimental investigations of flow past spinning circular cylinders were performed. Understanding and control of such flows are crucial to the design of efficient projectile based munitions. Experiments were conducted in an induction-type low-speed wind tunnel that includes a flow-conditioning section, a contraction with a 10:1 area ratio, a plexi...

A generalized eddy viscosity model is formulated by using the rotation modified energy spectrum. Rotation and mean shear effects are directly included in the eddy viscosity without the use of the local equilibrium assumption. The formulation also includes the modeling of vortex stretching and viscous destruction terms of the dissipation rate equati...

A turbulence model based on recursion renormalization group theory is modified to include rotational effects utilizing phenomenological treatment of the energy spectrum [Zhou, Phys. Fluids, Aug., 1995]. A dissipation rate equation with rotation rate dependent model coefficients is developed and validated using various benchmark test cases. The mode...

A generalized eddy viscosity model is formulated by using the rotation modified energy spectrum. Rotation and mean shear effects are directly included in the eddy viscosity without the use of the local equilibrium assumption. Since the model is of a general form, additional modifications to the eddy viscosity for non-equilibrium effects are not nee...

A two-equation turbulence model suitable for the analysis of flows with curvature and rotation is developed by reformulating the vortex stretching and the viscous destruction terms in the dissipation rate equation. The phenomenological treatment of the energy spectrum proposed by Zhou (Zhou, Phys. Fluids), v7, 2092, 1995 is modified to include the...

Reynolds stress closure models based on the recursion renormalization group theory are developed for the prediction of turbulent separated flows. The proposed model uses a finite wavenumber truncation scheme to account for the spectral distribution of energy. In particular, the model incorporates effects of both local and nonlocal interactions. The...

It is shown in this paper that the original version of the renormalization group K-epsilon model substantially underpredicts the reattachment point in the backstep problem - a deficiency that is traced to the modeling of the production of dissipation term. However, with recent improvements in the renormalization group K-epsilon model proposed by Ya...

Turbulence models are developed by supplementing the renormalization group (RNG) approach of Yakhot and Orszag with scale expansions for the Reynolds stress and production of dissipation terms. The additional expansion parameter (eta) is the ratio of the turbulent to mean strain time scale. While low-order expansions appear to provide an adequate d...

The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equ...

A numerical study of fully-developed turbulent flow past a backward-facing step is performed to analyze the effect of mesh refinement on the computed results. The time-averaged equations of conservation of mass and momentum are solved by a finite-volume method using two versions of the K-epsilon model of turbulence. The computations are performed w...

The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equ...

A recently developed K-tau model for near wall turbulent flows is applied to a variety of test cases. The turbulent flows considered include the incompressible flat plate boundary layer with adverse pressure gradients, incompressible flow past a backward facing step, and the supersonic flat plate boundary layer at zero pressure gradient. Calculatio...

The occurrence of secondary flow in curved ducts due to the centrifugal forces can often significantly influence the flow rate. In the present work, the secondary flow of an incompressible viscous fluid in a curved duct is studied by using a finite-volume method. It is shown that as the Dean number is increased the secondary flow structure evolves...

The pressure driven, fully-developed turbulent flow of an incompressible viscous fluid in curved ducts of square-section is studied numerically by making use of a finite volume method. A nonlinear Kappa - Iota model is used to represent the turbulence. The results for both straight and curved ducts are presented. For the case of fully-developed tur...

A numerical study of the secondary flows which occur in the laminar pressure-driven motion of dilute polymer solutions in ducts of rectangular cross-section is presented. The full nonlinear equations of motion for a Maxwell fluid with shear thinning are solved by an explicit finite-difference technique. Results are presented in an inertial framing...

A numerical investigation is conducted on secondary flows and roll-cell instabilities in the laminar channel flow of dilute polymer solutions subjected to a steady spanwise rotation. Finite difference calculations of the full nonlinear equations of motion for a Maxwell fluid and a Rivlin-Ericksen fluid of the second grade are presented which indica...

Computation of the flow field around a projectile moving through a gun barrel is a complex problem. The complications are due to presence of numerous factors, such as turbulence, compressibility, anisotropy of the stress field, complexities due to surface geometry, and change of the computational domain in time. In this study, calculation of the fl...