Direct numerical simulation of incompressible axisymmetric flows
Abstract
In the present work, we propose to conduct direct numerical simulations (DNS) of incompressible turbulent axisymmetric jets and wakes. The objectives of the study are to understand the fundamental behavior of axisymmetric jets and wakes, which are perhaps the most technologically relevant free shear flows (e.g. combuster injectors, propulsion jet). Among the data to be generated are various statistical quantities of importance in turbulence modeling, like the mean velocity, turbulent stresses, and all the terms in the Reynoldsstress balance equations. In addition, we will be interested in the evolution of largescale structures that are common in free shear flow. The axisymmetric jet or wake is also a good problem in which to try the newly developed bspline numerical method. Using bsplines as interpolating functions in the nonperiodic direction offers many advantages. Bsplines have local support, which leads to sparse matrices that can be efficiently stored and solved. Also, they offer spectrallike accuracy that are C(exp O1) continuous, where O is the order of the spline used; this means that derivatives of the velocity such as the vorticity are smoothly and accurately represented. For purposes of validation against existing results, the present code will also be able to simulate internal flows (ones that require a noslip boundary condition). Implementation of noslip boundary condition is trivial in the context of the bsplines.
 Publication:

Annual Research Briefs, 1994
 Pub Date:
 December 1994
 Bibcode:
 1994arb..nasa..373L
 Keywords:

 Axisymmetric Flow;
 Computational Fluid Dynamics;
 Computerized Simulation;
 Free Flow;
 Incompressible Flow;
 Shear Flow;
 Spline Functions;
 Turbulent Jets;
 Turbulent Wakes;
 Boundary Conditions;
 Fourier Transformation;
 NavierStokes Equation;
 Reynolds Stress;
 Turbulence Models;
 Vectors (Mathematics);
 Velocity Distribution;
 Fluid Mechanics and Heat Transfer