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Search: Posts Made By: kkpal
Forum: Main CFD Forum May 17, 2013, 21:30
Replies: 25
Views: 2,499
Posted By kkpal
dear all my problem of getting smaller Str...

dear all

my problem of getting smaller Str number is now solved.

It turns out that my mesh is Ok, the problem lies in the under-relaxation factor I employed in this unsteady cases. It is found...
Forum: Main CFD Forum May 17, 2013, 06:59
Replies: 25
Views: 2,499
Posted By kkpal
Philipp: here is a zoom in look of the mesh near...

Philipp: here is a zoom in look of the mesh near the cylinder. I've tried dividing the perimeter of the cylinder into 128 and 200, but with no luck.

Sijal: here is a picuture of the Cl plot.
For...
Forum: Main CFD Forum May 17, 2013, 02:58
Replies: 25
Views: 2,499
Posted By kkpal
The result of convergence level 1e-12 has come...

The result of convergence level 1e-12 has come out. St remains 1.44.
It seems the problem does not come from convergence level.

the numerical schemes I'm using is like this:
ddtSchemes
{
...
Forum: Main CFD Forum May 17, 2013, 02:48
Replies: 25
Views: 2,499
Posted By kkpal
For Far: yes, I made a mistake in the previous...

For Far:
yes, I made a mistake in the previous post.
My St is 0.14 while the accurate one should be 0.16.
I'm trying lowering the convergence level to 1e-12 because lowering to 1e-18 really takes...
Forum: Main CFD Forum May 16, 2013, 11:06
Replies: 25
Views: 2,499
Posted By kkpal
yes, that's what i mean. my St number is 1.4,...

yes, that's what i mean. my St number is 1.4, which I think is too low. actually according to the references i found, St should be around 1.65 when Re is 100.
If you have time, please help me with...
Forum: Main CFD Forum May 16, 2013, 10:49
Replies: 25
Views: 2,499
Posted By kkpal
here is a picture of the domain and mesh. mesh...

here is a picture of the domain and mesh.
mesh information:
70900 elements
47488 vertices

by the way, do you have a similar mesh file that yields good St number? if you have, could you please...
Forum: Main CFD Forum May 16, 2013, 10:40
Replies: 25
Views: 2,499
Posted By kkpal
My timestep is decided by the Courant number=0.5,...

My timestep is decided by the Courant number=0.5, in my case deltaT is around 0.01s. Suppose St=0.2, vortex shedding period is around 5s, so there are 500 timesteps for each shedding cycle.

" the...
Forum: Main CFD Forum May 16, 2013, 09:00
Replies: 25
Views: 2,499
Posted By kkpal
the density rho is set to be 1, and the kinematic...

the density rho is set to be 1, and the kinematic viscosity is 0.01. With velocity=1 and Diameter=1, that makes Re =100.
the software I'm using is OpenFoam.
I get quite good result in terms of...
Forum: Main CFD Forum May 16, 2013, 08:33
Replies: 25
Views: 2,499
Posted By kkpal
Thank you for your quick reply. upstream, top...

Thank you for your quick reply.
upstream, top and bottom distance are all 20D, downstream 40D. I've tried refine my mesh, but the result is not satisfactory.
Forum: Main CFD Forum May 16, 2013, 08:07
Replies: 25
Views: 2,499
Posted By kkpal
a little smaller Strouhal number

hi everyone!
I am simulating flow around cylinder at Re=100. But no matter how I tried, the St number I am obtaining remains 1.4, for which an accurater one is 1.6.
does someone have any suggestion...
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