Dissertation Work - Compressible Channel Flow Solver

Question 1

what you did in Dissertation

Answer 1

My dissertation work was on the DEVELOPMENT OF COMPRESSIBLE TURBULENT CHANNEL FLOW SOLVER.

The solver was written in fortran90 and simulation performed for Ma =1.5 and Re =3000 and results compared with that of Coleman, Kim and Moser.

A part from computing means & rms, we computed 2 point correlations, power spectrum visualized streaks and coherent structures.

Question 2

Work in Detail

Answer 2

A finite-difference based compressible turbulent channel flow solver.
Convective terms are discretized using QUICK (third-order upwind) or fourth-order central differencing based on cell Peclet based approach.
Diffusive terms are handled using fourth-order central differencing.
Convective & diffusive terms are treated explicitly while Runge-Kutta method (R-K 4) is used for time advancement.

Simulation has been performed at M a = 1.5 and Re b = 3000 and validated with the results of Coleman, Kim and Moser (CKM).
There is a good agreement between our results and that of CKM. Apart from computing mean and rms statistics, we have computed two-point correlations, power spectrum and have drawn near-wall streaks & vortical structures.

Question 3

Streaks

Answer 3

streaks - are regions of low and high-speed fluid flow along the streamlines.

Question 4

Coherent structures

Answer 4

A coherent structure is a connected turbulent fluid

mass with instantaneously phase-correlated vorticity over its spatial extent.

Question 5

Qinvaraint

Answer 5

second invariant of the velocity gradient tensor - (denoted as Q), primarily used for the visualization of coherent structures in turbulent flow.

Question 6

Finding, future work

Answer 6

Test this solver for various cases like one having discontinuities, etc.

Question 7

QUICK

Answer 7

QUICK (Quadratic Upwind Interpolation for Convection Kinematics)