A stable high order numerical scheme for direct numerical simulation (DNS) of shock-free compressible turbulence is presented. The method is applicable to general geometries. It contains no upwinding, artificial dissipation, or filtering. Instead the method relies on the stabilizing mechanisms of an appropriate conditioning of the governing equations and the use of compatible spatial difference...

NON-EQUISPACED FAST FOURIER TRANSFORMS IN TURBULENCE SIMULATION SEPTEMBER 2017 ADITYA MOHAN KULKARNI, B. E., UNIVERSITY OF PUNE M.S.M.E. UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Prof. Stephen de Bruyn Kops Fourier pseudo-spectral method is one of the approaches used to compute the derivative of a discrete data in Computational Fluid Dynamics. The Fourier transform of the data sampled on...

Climate varies on decadal and longer time scales, yet climate simulations advance at intervals measured in minutes or even seconds. In 1967, however, Edward Lorenz observed: “More than any other theoretical procedure, numerical integration is also subject to the criticism that it yields little insight into the problem. The computed numbers are not only processed like data but they look like dat...

We take inspiration from the turbulent Rayleigh-B\`enard flow of Pi Chamber and consider a particle-laden direct numerical simulation (DNS). The aim our study is to develop simple stochastic model that can accurately describe residence times particles in flow. underlying conceptual picture based on repeated trips between top bottom boundaries, driven by convective cells occur turbulence. Beyond...

A direct numerical simulation (DNS) of a channel flow with one curved surface was performed at moderate Reynolds number (Reτ = 395 at the inlet). The adverse pressure gradient was obtained by a wall curvature through a mathematical mapping from physical coordinates to Cartesian ones. The code, using spectral spanwise and normal discretization, combines the advantage of a good accuracy with a fa...

This paper presents numerical results obtained by applying an LES model based on a rational subdiagonal Pad e approximation in the wave number space We used a spectral element code to test this LES model a coarse DNS and the Smagorinsky model with Van Driest damping in the numerical simulation of a D channel ow at Re The corresponding results were compared with the ne DNS simulation of Moser Ki...

A method for generating inflow conditions for direct numerical simulations (DNS) of spatially-developing flows is presented. The proposed method is based on variational data assimilation and adjoint-based optimization. The estimation is conducted through an iterative process involving a forward integration of a given dynamical model followed by a backward integration of an adjoint system define...

Four widely-used techniques for vortex detection in turbulent flows are investigated and compared. The flow of a viscous incompressible fluid in a plane channel is simulated numerically by means of a parallel computational code based on a mixed spectral-finite difference algorithm for the numerical integration of the Navier-Stokes equations. The DNS approach (Direct Numerical Simulation) is fol...

This paper presents the results of a numerical simulation to determine hydraulic resistance for transverse flow through bundle hexagonal rods. The calculations were carried out using precision CFD code CONV-3D, intended direct an incompressible fluid (DNS-approximation) in parts fast reactors cooled by liquid metal. obtained dependencies pressure drop and coefficient anisotropy friction on Reyn...

An improved Eulerian method with a novel morphologic model is developed based on the direct numerical simulation (DNS) approach to study local scour. A movable immersed boundary proposed prescribe geometry of riverbed. Two techniques, namely Simultaneous Bed Adjustment Method (SBAM) and (Segment Plane Method) SPM, are complex time changing The SBAM technique considers sand sliding in SPM an alg...