|
[Sponsors] |
November 26, 1999, 11:50 |
Unsteady Boundary Conditions
|
#1 |
Guest
Posts: n/a
|
Hi, Could anyone tell be if they have had any experience using unsteady boundary conditions in CFX4.2 using the USRBCS FORTRAN routine. I'm interested in modelling an NACA0012 aerofoil with a transient inflow boundary condition. So far i've managed to implement an oscillating inflow condition in the USRBCS FORTRAN routine and obtained transient solutions. However, when you look at the dump file after a no of periods there doesn't seem to be any downstream wake response.The Lift & Drag force's are changing. Could someone shed some light on these initial findings? Am i doing someting fundamentally wrong!!
Regards James Date |
|
November 29, 1999, 08:09 |
Re: Unsteady Boundary Conditions
|
#2 |
Guest
Posts: n/a
|
Hi James.
I have been using USRBCS successfully for varying the inlet flow of a centrifugal pump for detecting hysteresis in rotating stall onset. So principally it should work, as far as I understand your case. If you have problems with the wake, perhaps the outlet boundary condition should be looked at. Regards, Erik Torbergsen |
|
November 29, 1999, 23:44 |
Re: Unsteady Boundary Conditions
|
#3 |
Guest
Posts: n/a
|
Hi James,
what is your outlet BC treatment and where is it? Also, what is your grid ie. do you have walls in the near field like an airfoil in a tunnel or do you use far field conditions? Regards, Duane |
|
November 30, 1999, 08:08 |
Re: Unsteady Boundary Conditions
|
#4 |
Guest
Posts: n/a
|
Hi Duane, Thanks for your reply.I'm using a C-Grid + H-Grid round the aerofoil.My outlet bounday is located 10 chord lengths down stream, i've set it as a constant pressure bounday (Is this correct?)The upper and lower boundaries on the grid i've also set as pressure boundaries. The inlet boundary condition is set in the user FORTRAN routine;i.e. Alpha(angle of attack)=Alpha0*sin(wt). U=V0*cos(Alpha), V=V0*sin(Alpha). Regards James Date
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
mass flow in is not equal to mass flow out | saii | CFX | 12 | March 19, 2018 05:21 |
unsteady boundary conditions | bephi | OpenFOAM Pre-Processing | 1 | March 30, 2011 15:31 |
[Netgen] boundary conditions and mesh exporting | vaina74 | OpenFOAM Meshing & Mesh Conversion | 2 | May 27, 2010 09:38 |
Unsteady boundary conditions | James Date | Main CFD Forum | 2 | March 5, 2001 13:54 |
A problem about setting boundary conditions | lyang | Main CFD Forum | 0 | September 19, 1999 18:29 |