|
[Sponsors] |
![]() |
![]() |
#1 |
New Member
Patrick Wayne
Join Date: Nov 2013
Posts: 3
Rep Power: 12 ![]() |
Hello,
I'm going crazy trying to figure out how to program a 1/7th power law velocity profile (FD) for my inlet on simple duct flow in Star-CCM+. I have very little experience in programming in general and even less experience in field functions, so I really don't know what to do. I tried going off of something in the "Help" section: [(($$Position[1] <= 0.0025) ? 1.0752*1.143*pow(($$Position[1]/0.0025),0.143) : 1.0752*1.143*pow(((0.005-$$Position[1])/0.0025),0.143)), 0, 0] Basically, it's u(y) = u_bar*(y/delta)^(1/7) for y <= 0.0025 m. and u(y) = u_bar*((h-y)/delta)^(1/7) for y > 0.0025 m. I know this is wrong because my simulation won't run with this. Can anyone help me? Thanks, P. Wayne p.s. The entire height of the duct is only 5 mm.....just in case you were wondering Last edited by pwayne; May 9, 2014 at 22:54. Reason: Forgot Something |
|
![]() |
![]() |
![]() |
![]() |
#2 |
New Member
|
Could you please post the error message from Star-CCM+ in order to understand what is not working.
Cheers |
|
![]() |
![]() |
![]() |
![]() |
#3 |
New Member
Patrick Wayne
Join Date: Nov 2013
Posts: 3
Rep Power: 12 ![]() |
I'll upload that as soon as possible. What I remember is that it says a floating point error has occured in regards to the segregated flow solver. Maybe that helps?
P.Wayne |
|
![]() |
![]() |
![]() |
![]() |
#4 |
Senior Member
Join Date: Nov 2010
Location: USA
Posts: 1,232
Rep Power: 24 ![]() |
Your field function looks fine. The problem probably lies with the mesh or BCs.
Does it blow up immediately or after some iteration? |
|
![]() |
![]() |
![]() |
![]() |
#5 |
New Member
Patrick Wayne
Join Date: Nov 2013
Posts: 3
Rep Power: 12 ![]() |
It blows up just after the first iteration. It's a relief to know the function is fine though, so thank you. I'll work on the Mesh, BCs, then we'll see what happens. I didn't gfet a chance to work on it today, but I'll dive into it tomorrow.
P.Wayne |
|
![]() |
![]() |
![]() |
Tags |
duct flow, field functions, power law, udf, velocity profile |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
3D UDF Paraboilc Velocity Profile (Can't Maintain) | Sing | FLUENT | 12 | August 7, 2017 06:25 |
Non-Newtonian Power Law for Viscosity | John | FLUENT | 16 | September 12, 2015 06:18 |
UDF for Inlet velocity | Mijin Kim | FLUENT | 0 | September 28, 2009 04:50 |
Non newtonian power law model in pipe annulus | Poly | FLUENT | 0 | March 24, 2005 15:12 |
Terrible Mistake In Fluid Dynamics History | Abhi | Main CFD Forum | 12 | July 8, 2002 09:11 |