Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Supersonic flow
Posted Jul 4, 2011, 3:30 a.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.1 2 Replies
Please login with a confirmed email address before reporting spam
The approach to the problem begins with a half cone geometry of 8* half-angle and a rectangular box(15-times larger than maximum dimension of half cone)
I am using COMSOL 4.1 with non-isothermal flow module(laminar)
The rectangular box has following boundary conditions
1>inlet-velocity,constant temperature
2>outlet-pressure,outflow
3>outer wall opposite to half-cone(slip)
4>wall containing half-cone(slip-axis symmteric)
5>half-cone surface(no slip)
Study Type
-stationary solver
Approach
I started with inlet velocity 20m/s and kept this as initial condition for inlet velocity 50m/s and so on in steps of 30m/s.
I refined the mesh as and when required as per the physics and the way of meshing was well taken care. As i increased inlet velocity, i was slowly decreasing outlet pressure also. The results were satisfactory till 250m/s-inlet and outlet pressure-0.4[atm].
Issue
After 250m/s with all possible and careful configuration of solver setting and meshing the results are distorted for
inlet-260m/s and after this it doesnot converge properly. Maximum i have gone upto 280/m/s-inlet with step increase reduced to 5m/s.
How can i curb this problem ?Do i need to change CFL number?
Additional information
>>Relative tolerence(0.001)
>>used both Pardiso or iterative(krylov-preconditioning) with fully coupled
>>cone is spherically blunted
>>automatic damping [varied both i)step for update(2-5) ii)minimum dampin factor(10^-4 to 10^-8)]
>>configuration of computer 8GB RAM quad core also 32GB RAM server was also used
>>Ck=0.5-0.75 was used in consistent stabilization
>>inconsistent stabilization was never used as it would affect the physics
Please login with a confirmed email address before reporting spam
The best way to model supersonic flows is to use the High Mach Number Flow (HMNF) interface available in COMSOL Multiphysics 4.2.
Best regards,
Zoran
Please login with a confirmed email address before reporting spam
Thank you for your reply. I am aware of the module(HMNF) in comsol 4.2. But all i want to know whether is it possible to use non-isothermal flow module for supersonic flow because i am presently using comsol 4.1. If at all there is no point in trying in non-isothermal flow i will switch to comsol 4.2 as you have advised.
GV