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Search: Posts Made By: sbaffini
Forum: Main CFD Forum August 9, 2022, 09:01
Replies: 8
Views: 158
Posted By sbaffini
Thanks, I have indeed also tried several...

Thanks, I have indeed also tried several combinations (note however that I cannot work with sound speed or density in my code, as preconditioning and my choice of independent variables makes them...
Forum: Main CFD Forum August 9, 2022, 05:47
Replies: 8
Views: 158
Posted By sbaffini
I probably misguided you by using a Fluent based...

I probably misguided you by using a Fluent based nomenclature.

What I am referring to is, exactly, a total pressure bc. That is, I know total pressure P0 and total temperature T0 at inlet. How do...
Forum: Main CFD Forum August 8, 2022, 12:56
Replies: 8
Views: 158
Posted By sbaffini
On the pressure inlet BC

Dear all,

I have a doubt about how a correct pressure inlet bc should be implemented and would like to hear from anyone who has coded this.

Let's first clarify that I'm talking about this...
Forum: Main CFD Forum August 8, 2022, 10:46
Replies: 5
Views: 172
Posted By sbaffini
Let's supersede the fact that NO, it is not ok...

Let's supersede the fact that NO, it is not ok for the unsteady residuals to show unpredictable behavior. Even if you were performing DNS, as long as done with the same code on the same machine and...
Forum: Main CFD Forum August 5, 2022, 05:06
Replies: 17
Views: 950
Posted By sbaffini
Thanks for the clarification. To give some...

Thanks for the clarification.

To give some context on why I used this method, consider that this was my first ever panel code, made for a university course.

Back then, I just tought that I...
Forum: Main CFD Forum August 4, 2022, 14:45
Replies: 17
Views: 950
Posted By sbaffini
Dear James, I see what you mean, but I have a...

Dear James, I see what you mean, but I have a doubt.

From what you say, I understand that in the source-doublet method with Dirichlet boundary conditions on the potential, using the local gradient...
Forum: Main CFD Forum August 4, 2022, 11:23
Replies: 3
Views: 103
Posted By sbaffini
Well, the problems might be everywhere (are...

Well, the problems might be everywhere (are meshes identical except for a scale factor?), but in general you clearly aren't solving two identical problems, and the fact that you only refer about...
Forum: Main CFD Forum August 4, 2022, 10:24
Replies: 17
Views: 950
Posted By sbaffini
I can only speak for the vortex ring case but,...

I can only speak for the vortex ring case but, few things are worth mentioning, as I don't know exactly how this translate to other approaches:

1) The issue for this method is just about the...
Forum: Main CFD Forum August 4, 2022, 07:59
Replies: 4
Views: 127
Posted By sbaffini
I haven't coded it myself, nor I use deferred...

I haven't coded it myself, nor I use deferred correction in the form typically presented (I use a density based solver in delta form), but the overall effect is indeed similar to the gradient...
Forum: Main CFD Forum August 4, 2022, 07:47
Replies: 17
Views: 950
Posted By sbaffini
My direct experience is only with a 3D vortex...

My direct experience is only with a 3D vortex ring method, which however is equivalent to a constant doublet one. In my case I had to add a surface gradient contribution, which I took from a slide of...
Forum: Main CFD Forum August 3, 2022, 12:33
Replies: 4
Views: 127
Posted By sbaffini
phi_intermediate is the value that phi would have...

phi_intermediate is the value that phi would have taken if relaxation was not present.

The explanation in the manual is not extra clear, but the idea is that the factor f multiplies the so called...
Forum: Main CFD Forum August 3, 2022, 11:22
Replies: 1
Views: 87
Posted By sbaffini
I remember having similar issues (a decade ago),...

I remember having similar issues (a decade ago), which are related to the parallel decomposition, but I honestly don't remember anymore when and why this happened, if it was my fault or Fluent fault,...
Forum: Fluent UDF and Scheme Programming August 3, 2022, 09:58
Replies: 16
Views: 806
Posted By sbaffini
No, I mean the part that I reported in my...

No, I mean the part that I reported in my previous post:

"Note: Note that all boundary conditions used by the MHD model must be set in the Boundary Condition tab of the MHD Model dialog box....
Forum: Fluent UDF and Scheme Programming August 3, 2022, 09:23
Replies: 16
Views: 806
Posted By sbaffini
I took some time and checked better. Two things: ...

I took some time and checked better. Two things:

1) Apparently, MHD module in Fluent is still based on UDF and UDS, so your findings seems coherent with the fact that MHD is based on UDS.

2)...
Forum: Fluent UDF and Scheme Programming August 3, 2022, 08:10
Replies: 16
Views: 806
Posted By sbaffini
Ok, you certainly don't need a define_adjust to...

Ok, you certainly don't need a define_adjust to simply assign a sinusoidal time variation to a BC. As I said, it is meant for other things.

Now, your scenario is very simple, and there certainly...
Forum: Fluent UDF and Scheme Programming August 3, 2022, 07:33
Replies: 16
Views: 806
Posted By sbaffini
Not sure I understand, nor I will be able to...

Not sure I understand, nor I will be able to check or help with any code now. But, you need to know the following, define_adjust is called at the beginning of each iteration and it is general,...
Forum: Main CFD Forum August 2, 2022, 08:38
Replies: 2
Views: 119
Posted By sbaffini
What is your difficulty? Because, in general, it...

What is your difficulty? Because, in general, it really sums up to simply not using the diffusion part from the convection-diffusion example.

For explicit schemes, of course, there are caveats,...
Forum: Main CFD Forum August 1, 2022, 16:46
Replies: 37
Views: 435
Posted By sbaffini
Dear James, I have to tell that the last...

Dear James,

I have to tell that the last time I worked on this topic is around 16 years ago, when I was actually trying to make a 3D, vortex rings only, panel method for closed and open bodies,...
Forum: Main CFD Forum August 1, 2022, 07:11
Replies: 37
Views: 435
Posted By sbaffini
Apologies again if my intervention seemed out of...

Apologies again if my intervention seemed out of place or contentious, the questions in my last answer were genuine. I want to understand what you two are saying because, now, I don't understand.
...
Forum: Main CFD Forum July 31, 2022, 03:57
Replies: 37
Views: 435
Posted By sbaffini
Ok, again apologies for the confusion, but Katz...

Ok, again apologies for the confusion, but Katz and Plotkin describe exactly this approach in the first 4 paragraphs of chapter 9. They even mention issues when the body gets too thin. So, is that...
Forum: Main CFD Forum July 30, 2022, 18:41
Replies: 3
Views: 124
Posted By sbaffini
Betchen, straatman and de groot seem to have...

Betchen, straatman and de groot seem to have worked more extensively on the subject, so their work might be a more reliable source. Yet, I have no idea of the fundamentals on the topic
Forum: Main CFD Forum July 30, 2022, 09:12
Replies: 37
Views: 435
Posted By sbaffini
Apologies if I make confusion over the comments...

Apologies if I make confusion over the comments of people knowing better than me but, maybe, what you miss is that a single source is just assigned to balance the local Vinf*n term. That is, all the...
Forum: Main CFD Forum July 30, 2022, 09:04
Replies: 3
Views: 124
Posted By sbaffini
I haven't worked yet on it, but this work does...

I haven't worked yet on it, but this work does that and includes additional references on the topic
...
Forum: Main CFD Forum July 28, 2022, 05:26
Replies: 3
Views: 140
Posted By sbaffini
The problem you have could be anything, even non...

The problem you have could be anything, even non UDF related. Probably it is some floating point exception in one process, or you are using some variable which is not initialized correctly....
Forum: Main CFD Forum July 27, 2022, 10:58
Replies: 9
Views: 160
Posted By sbaffini
The point is that this kinda means nothing in...

The point is that this kinda means nothing in quantitative terms. Have you ever seen how rubbish a first order solution can look while still being quite there in terms of formal accuracy?

So, in...
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