CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Problem with pseudo shock simulation!

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   September 5, 2012, 05:38
Post Problem with pseudo shock simulation!
New Member
Join Date: Aug 2012
Posts: 2
Rep Power: 0
Sridhar thiru is on a distinguished road
Hi Guys!! am doing simulation on constant area straight ducts which mimics supersonic inlet isolators, i would like the study the pseudo shock phenomenon that occurs due to shock wave boundary layer interactions.

My problem domain is a cuboid with dimension 80x80x960 all in mm..
owing to computation i reduced the cross section dimension to 40x40 mm, with two long faces of cuboid set to symmetry. n length remained same.

Grid : cuboid with above dimensions;
structured grid with grid fined near the corner region,
1.5 million hexahedral cells, cell squish is around 0.2

Solver settings:
Density based, implicit, absolute velocity formulation.
Material, Air as ideal gas, viscosity :sutherlands formulation.
Turbulence model: standard K - omega model with low re number effect & shear flow corrections enabled,

Boundary conditions are as follows,

Pressure inlet :
momentum- tot pressure 196000pa
supersonic int gauge pressure - 25050 pa
Turbulence parameters
Hydraulic diameter 0.08m
intensity 5 %
Total Temperature : 300k

pressure outlet :
momentum-gauge pressure - 25050 pa
Turbulence parameters
Hydraulic diameter 0.08m
intensity 5 %
Total temperature : 300k

wall : no slip & stationary, heat flux set to zero (adiabatic!)

symmetry : default symmetry

Solver is a STEADY SOLVER ( just to obtain initial conditions for UNSTEADY SOLVER)

flux : AUSM
flow : third order MUSCL
Turbulence scalar equations : QUICK
CFL set to default value of 5.

wall y+, i calculated using NASA viscous grid spacing calculator i fixed y+ of 30 which throws cell height of 1e-5m!! is 3.8*e6 with reference length as hydraulic diameter..

The problem is my solution is not converging beyond 1e-5, residuals fluctuate around 1e-5.. i set the convergence criteria to 1e-6.!!

Is it enough to switch to unsteady solver???
If that the case what value of time step i provide?? also max iterations per time step..I'm stuck with this, Help me..

Also when check with the contour, fluent shows the max wall y+ value of 19 near the wall though i set the cell height for y+ 30.

Thanks in advance.
Sridhar thiru is offline   Reply With Quote


pseudo shock, ramjet isolator, supersonic internal flows, turbulence model

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
the shock tube problem and its artifacts with sonicFoam emjay OpenFOAM Running, Solving & CFD 0 December 16, 2011 08:58
Turbine: Transient Simulation Problem John C. CFX 7 December 5, 2011 09:31
[ask] shock absorber simulation dik Main CFD Forum 1 December 17, 2009 02:32
CFX converge problem caused by shock waves littlelz CFX 3 August 17, 2009 09:35
tracer simulation for transient problem. John CFX 0 August 12, 2005 10:37

All times are GMT -4. The time now is 16:39.