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Search took 0.00 seconds. Search: Posts Made By: rks171
Forum: Main CFD Forum March 25, 2012, 15:11
Replies: 39
Views: 10,603
Posted By rks171
I was not aware that it would be possible to...

I was not aware that it would be possible to fully resolve my BL with such few cells. It's something I'm just going to play around with in the future. I won't have the time to do that for a while,...
Forum: Main CFD Forum March 24, 2012, 17:55
Replies: 39
Views: 10,603
Posted By rks171
Thank you for the information. I agree that the...

Thank you for the information. I agree that the mesh is a likely culprit considering the problems that I had with just obtaining convergence that were solved by mesh modification. At this point,...
Forum: Main CFD Forum March 23, 2012, 19:03
Replies: 39
Views: 10,603
Posted By rks171
I'm going to have to get a lot better at making...

I'm going to have to get a lot better at making my meshes. Having 12 prism layers to resolve the BL is just not going to work for my model. It would be way too computationally expensive. ...
Forum: Main CFD Forum March 19, 2012, 17:03
Replies: 39
Views: 10,603
Posted By rks171
Sorry for taking so long to reply back to this...

Sorry for taking so long to reply back to this thread, but I got tied up in some other work and never ended up getting to that thicker wall prism layer case until now. To sum up the overall results...
Forum: Main CFD Forum January 31, 2012, 16:50
Replies: 39
Views: 10,603
Posted By rks171
As far as I know, no I'm not fully resolving the...

As far as I know, no I'm not fully resolving the boundary layer. I selected the all y+ wall treatment. It's a wall function. And the thickness of those two prism layers (originally 2) was about...
Forum: Main CFD Forum January 31, 2012, 10:01
Replies: 39
Views: 10,603
Posted By rks171
Thanks for the link. The first case that I ran,...

Thanks for the link. The first case that I ran, where I added a third prism layer, didn't solve nicely at all. After 2E6 CPU seconds, the solution only reached 230 iterations and crashed due to...
Forum: Main CFD Forum January 30, 2012, 16:33
Replies: 39
Views: 10,603
Posted By rks171
The drawing you posted is a little off. The...

The drawing you posted is a little off. The 'obstruction zone' that I was referring to is the area in the direct vicinity of the obstruction (red rectangle in the picture below). Everything else...
Forum: Main CFD Forum January 30, 2012, 14:46
Replies: 39
Views: 10,603
Posted By rks171
I appreciate your effort on coming up with that...

I appreciate your effort on coming up with that proof, but please hear out my methodology. First, I must appologize because when I wrote that previous post saying that the total section pressure...
Forum: Main CFD Forum January 30, 2012, 12:53
Replies: 39
Views: 10,603
Posted By rks171
This was right... That's how I...

This was right...



That's how I calculated the error of the calculated bare section pressure drop.

This...
Forum: Main CFD Forum January 30, 2012, 09:42
Replies: 39
Views: 10,603
Posted By rks171
Of course, the form loss is a big contributor to...

Of course, the form loss is a big contributor to the head loss. I am aware of this, but you do raise a good point. I checked the bare section pressure drop to the section with obstruction. A...
Forum: Main CFD Forum January 29, 2012, 11:19
Replies: 39
Views: 10,603
Posted By rks171
I've seen other posts where ppl said y+ should be...

I've seen other posts where ppl said y+ should be above 30 always, however, I think that's if you're using a high y+ wall treatment. I'll check how the y+ differs between the obstructions and the...
Forum: Main CFD Forum January 28, 2012, 17:28
Replies: 39
Views: 10,603
Posted By rks171
Yes, I'm sorry I was not clear about that before....

Yes, I'm sorry I was not clear about that before. I'm trying to model the entire experimental test section, which includes both the obstructions and the bare flow region. You are correct that Re is...
Forum: Main CFD Forum January 28, 2012, 12:58
Replies: 39
Views: 10,603
Posted By rks171
Do I have a choice whether or not I use a wall...

Do I have a choice whether or not I use a wall function? I thought I needed to use one with the k-epsilon turbulence model. Right now I'm using two-layer all y+ wall treatment.

As for...
Forum: Main CFD Forum January 28, 2012, 08:06
Replies: 39
Views: 10,603
Posted By rks171
That all makes sense. My Reynolds number is...

That all makes sense.

My Reynolds number is based on the hydraulic diameter of my flow channel. Should I be aiming for a certain y+ value on the straps in order to better predict the wall drag? ...
Forum: Main CFD Forum January 27, 2012, 19:29
Replies: 39
Views: 10,603
Posted By rks171
Mach number, I don't know... it's incompressible...

Mach number, I don't know... it's incompressible and the Reynolds number is about 100,000. Blockage ratio, I think, was about 30%, but I'll have to get back to you on that if that's important. I'll...
Forum: Main CFD Forum January 27, 2012, 18:36
Replies: 39
Views: 10,603
Posted By rks171
Well, the accuracy of the flow velocity...

Well, the accuracy of the flow velocity prediction is within about +- 10% for like 80% of the measurement points. I don't know if this should be considered good or not. I was using the realizable...
Forum: Main CFD Forum January 27, 2012, 13:01
Replies: 39
Views: 10,603
Posted By rks171
Pressure drop not correctly predicted

I'm modeling an experiment with a flow obstruction and predicting the pressure drop that was measured in that test section. However, my prediction is about 26% under-predicted from the experimental...
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