creating Lids in FloWorks

[EMS21]

Hi
I've done the tutorial for the Ball Valve in Floworks with out any hitch's, So I created a new project for a Fan Shroud, but when I create a new Boundry condition I get an error that says...
Face <2Lid Center-1@Extrude1> is not laying on the boundary between solid and fluid region.

is it because the Inlet opening is a Rectangular shape ? round Lids like the one used in the Ball Valve work just fine as a test in another project.

I'm using CFW2006

What have I missed
TIA
Thomas

 

[cbrn]

Hi,
no, it's not because of the shape. It depends upon how your lid is touching the conduit: I don't remember if it doesn't like cylindrical mating (the lid is inside the conduit) or planar mating (the lid is outside the conduit), but one of the two is always giving problems...

Regards

 

[EMS21]

Hi
I basicaly got it all working ok but with mixed results for the lids,(Perhaps a Tutorial about Lids could be explained in some more detail) I changed my Lids and the Model so that there was no longer a radius in the 4 corners of the rectangle, not what I wanted but ... it worked!

In another thread that making the lids bigger in order to easily select the Face/Boundary,

http://www.eng-tips.com/viewthread.cfm?qid=162141&page=1

wouldn't this tell the solver that the boundary area is bigger than it should be or is the solver able to figure this out ?

I tried this making the Lid a little bigger so that it does intersect the Conduit however it works ok with the Ball valve but not my origional Fan Shroud ??

In the Wizard for Result Resolution if the "Manual specification of the gap size " box is ticked for a minimum flow passage of whatever value x.xx m does this have anything to do with lid not Laying on the Boundary between the Solid and the Fluid regions or any Gaps that may exist between the Lid and the Solid ?

TIA
Thomas

 

[cbrn]

Hi,
1- making lids a bit bigger won't puzzle the solver: the recognition of the fluid volume is based upon the SolidWorks' boolean operations and, to make it simple, searches for the number of "solid intersections" and "closed volumes" to find out what is "in" and what is "out". Theoretically, a perfect co-planarity or a perfect tangency should be recognized as a "continuum", but in some cases FloWorks doesn't interprete this correctly (even if SolidWorks' engine does: you can try it by operating a boolean on the tangent bodies).
Why this works with some geometry and not with some other depends on many geometrical factors and it's not easy to find it out without seeing your geometry.
2- the "min flow passage" should not interfere with this process, unless it is set so low that it becomes less than the topological tolerance of the solid model (almost impossible, IMO). BUT, it will interfere if you do have intentional gaps (but this should never happen for the lids). In adition, I've been explained, back when I used to use FloWorks and it was in v.2004, that this setting is in reality not a direct dimension value but rather a sort of "relative threshold"; I don't remember it better than this: perhaps asking directly your support will allow you to receive specific info.

Regards

 

[EMS21]

Thanks for the answer's, a bit of insight goes a long way,
I'll keep playing around some more untill i break something !

Thankyou
Thomas