Floworks: streamlines passing THRU solid :(

[CalculatorDave]

Howdy all,

In Floworks, I am seeing fluid streamlines passing, erroneously, right through a solid assembly.

I am running a Floworks analysis of fluid flow over the exterior of an assembly. I ran several analyses very successfully. BUT, when I made a small change to the assembly (and had Floworks then "rebuild" it), then re-ran the solver, the Floworks analyses show the fluid streamlines passing right THROUGH the solid assembly. This must be a problem with meshing, but why would it happen now, when I've been running other case studies successfully? How can I correct this problem?

David

 

[cbrn]

Hi,
maybe a gap is now "seen" by the algorythm which tries to recognize what is "inside" and what is "outside" a solid volume. I stopped using FW when it was still on v.2004, but in this time problems like yours were common when the "caps" were made with tangent faces. Back in this time, it was one of the most painful weaknesses of FW, though easily "workaroundable".

Regards

 

[hiyer]

Hi,

You have the option of creating just the mesh in CFW before running the analysis. I would suggest using this to make sure that all the features are properly resolved by the mesher after you make changes to the model. If the automatic mesh settings are not resolving the solid & fluid regions properly then you might have to use manual mesh settings.

Regards,
H

 

[Nettuno]

Hi,

If I understood correctly your analysis has been correctly completed by the solver and you have a problem with the "Cut Plots" overview, am I right? I'm using FW 2004 and last year I had a similar problem working with a Flow Internal Analysis across a valve in a pipe. After performing a first Analysis I had cloned the Project, changed the pipe size and then re-run the analysis. In order to overview the results I used the same Cut Plot already present (cloned from the first analysis) and the stream flow displayed was not correctly defined around the pipe. After some attempt I found that the problem was the pre-existent Cut Plot feature that for some unknown reason had the same computational domain of the first analysis. So I solved the problem deleting the pre-existing Cut Plot and creating a new one ...

BR
Mirko

 

[CalculatorDave]

Problem solved.

It was simply that my Initial Mesh settings (the default ones chosen by FloWorks) were too coarse. When I manually selected the gap size and wall thickness values, everything ran fine. You would THINK that FloWorks would choose default values that were appropriate.