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Showing results 1 to 16 of 16 Search took 0.00 seconds. Search: Posts Made By: sbaffini

Forum: FLUENT August 13, 2015, 17:58

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini I mean, there is no node implied, just cells. ... I mean, there is no node implied, just cells. However, for the record, in a finite difference setting you would have used the source term for each of the nodes you are actually solving for.

Forum: FLUENT August 13, 2015, 17:54

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Well, in finite volume, the source term is... Well, in finite volume, the source term is applied on a cell by cell basis, just like the pressure gradient. This means that it is simply applied to all the cells.

Forum: FLUENT August 13, 2015, 17:43

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Ahmed, what do you mean by something wrong... Dear Ahmed, what do you mean by something wrong in the unsteady part? You just need to add this as classical source term (Fluent knows how to do that) under cell zone conditions. I am on the...

Forum: FLUENT April 26, 2015, 04:44

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Please, read the UDF manual on how to add a... Please, read the UDF manual on how to add a momentum source term in Fluent. If you know how to do that, you can certainly use my udf above for thst purpose. Once you do that, addong periodicity with...

Forum: FLUENT April 24, 2015, 12:11

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Well: 1) Setup periodicity as usual but... Well: 1) Setup periodicity as usual but leave the pressure gradient as 0 2) Add a momentum source term using the supplied udf In order for this to work as expected you have to modify the udf...

Forum: FLUENT April 23, 2015, 18:07

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Notice that you don't need to use it under the... Notice that you don't need to use it under the periodic panel. Just use the source term in a classical sense. This is the way the pressure gradient is fixed by Fluent itself (it's just a source term)

Forum: FLUENT April 9, 2015, 14:05

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Ahmed, You just need an UDF with a... Dear Ahmed, You just need an UDF with a momentum source term dependent on time. This just represents the opposite of the pressure gradient you would tipically use. Find attached a trivial...

Forum: FLUENT May 23, 2014, 09:40

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Following my previous discussion i would change... Following my previous discussion i would change the pressure interpolation. However, my answer can only be incomplete without knowing additional details on your simulation, like the time advancement,...

Forum: FLUENT May 23, 2014, 07:07

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Notice that, currently, Fluent guidelines... Notice that, currently, Fluent guidelines discourage the use of the PRESTO for LES, which is described as overly diffusive. Actually, my results indicate that are the other schemes being only...

Forum: FLUENT May 23, 2014, 07:00

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Philipp, the PRESTO issue for Fluent is... Dear Philipp, the PRESTO issue for Fluent is a longstanding one as, roughly speaking, no one knows what it exactly does. I cannot give you a straight answer but, if you want, you can read part of...

Forum: FLUENT November 21, 2012, 06:41

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear rasoulb, notice that in the work of... Dear rasoulb, notice that in the work of Abe et al., the flow is driven by a fixed pressure gradient. As a consequence, while it is perfectly fine to compare the skin friction coefficient, its...

Forum: FLUENT November 18, 2012, 09:56

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Rasoul, as a first guess i suggest you... Dear Rasoul, as a first guess i suggest you to proceed with the fixed pressure gradient periodic boundary condition, just to check that everything is fine (than, possibly, use a fixed mass flow...

Forum: FLUENT September 3, 2012, 06:42

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Javier, the main fact to know about... Dear Javier, the main fact to know about the square/ractangular channel is that the wall stress distribution along the section perimeter is, of course, not constant. Especially in the middle of...

Forum: FLUENT June 28, 2012, 04:02

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Javier, if you are using periodic boundary... Dear Javier, if you are using periodic boundary conditions the main criterion to check about the convergence toward a statistically steady state is to monitor the volume average of the resolved...

Forum: FLUENT June 21, 2012, 08:47

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini In my experience, the grid size requirements for... In my experience, the grid size requirements for a wall bounded LES are (for a low order code like Fluent): streamwise: dx+ <=30-60 wall-normal: dy+_min <1 - dy+_max < = 30 (probably it can be...

Forum: FLUENT June 19, 2012, 09:12

Replies: 34 Periodic Pipe Flow LES; parabolic profile Views: 5,764 Posted By sbaffini Dear Javier, if i understood well, you are... Dear Javier, if i understood well, you are simulating the pipe flow at Re_tau = 320 (DNS of Wagner and Huttl, C&F). The first issue, in your case, is probably the velocity field...

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