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Search: Posts Made By: praveen
Forum: Main CFD Forum March 6, 2022, 23:34
Replies: 2
Views: 1,241
Posted By praveen
I like https://asymptote.sourceforge.io/ for this.

I like https://asymptote.sourceforge.io/ for this.
Forum: Main CFD Forum November 16, 2021, 00:49
Replies: 5
Views: 646
Posted By praveen
Gmsh seems to be best freely available grid...

Gmsh seems to be best freely available grid generator for unstructured grids, so having ability to read in gmsh format is good. It is easy to add other formats to read in, you will have to write your...
Forum: Main CFD Forum September 30, 2021, 07:51
Replies: 2
Views: 420
Posted By praveen
Can you give some examples of what you are...

Can you give some examples of what you are talking about ?
Forum: Main CFD Forum September 30, 2021, 07:32
Replies: 13
Views: 946
Posted By praveen
1-based is good for computational work. Fortran...

1-based is good for computational work. Fortran has the best of all since it allows you to change the indexing, even negative indexing, which is great for writing pde solvers.

Some languages like...
Forum: Main CFD Forum July 24, 2021, 03:05
Replies: 5
Views: 574
Posted By praveen
You will have the problem of very small cells...

You will have the problem of very small cells which will impact time step in explicit schemes.

There are some works that deal with small cut cells and resulting time step issue, e.g.,
...
Forum: Main CFD Forum June 28, 2021, 06:53
Replies: 9
Views: 1,112
Posted By praveen
I am very interested to know how people allocate...

I am very interested to know how people allocate multi-dimensional arrays.

For example, on a 3d structured grid, one needs to store data like this

double sol[nx][ny][nz][nvar];

This is easy...
Forum: OpenFOAM June 10, 2021, 09:59
Replies: 11
Views: 3,259
Posted By praveen
Seems to be here now ...

Seems to be here now

https://sourceforge.net/p/gfoam/code/HEAD/tree/
Forum: Main CFD Forum April 10, 2021, 03:26
Replies: 33
Views: 1,903
Posted By praveen
Stability issues are discussed in a bad and wrong...

Stability issues are discussed in a bad and wrong way in many CFD books. This is the problem even in the recent book

Hirsch, Numerical computation of internal and external flows. Volume 1

There...
Forum: Main CFD Forum April 10, 2021, 03:02
Replies: 33
Views: 1,903
Posted By praveen
Gershgorin cannot decide either way, but you can...

Gershgorin cannot decide either way, but you can compute eigenvalues since you have a circulant matrix. See the attached note.

Be careful when using eigenvalues when the matrix is non-normal,...
Forum: Main CFD Forum March 1, 2021, 03:57
Replies: 9
Views: 824
Posted By praveen
My favourite is McQuarrie, Statistical...

My favourite is

McQuarrie, Statistical Mechanics

It covers the topics you listed.
Forum: Main CFD Forum February 25, 2021, 08:07
Replies: 6
Views: 692
Posted By praveen
Have you looked at "Expression Templates", see ...

Have you looked at "Expression Templates", see

https://en.wikipedia.org/wiki/Expression_templates

It describes almost same situation which you are asking.
Forum: Main CFD Forum February 25, 2021, 02:32
Replies: 6
Views: 692
Posted By praveen
You can define an add function class...

You can define an add function


class VECTOR
{
void add(VECTOR& a, VECTOR& b);
};

VECTOR a, b, c;
a.add(b, c); // a = b + c
Forum: Main CFD Forum January 26, 2021, 08:32
Replies: 25
Views: 1,499
Posted By praveen
Just ask https://twitter.com/HiroNishikawa on...

Just ask https://twitter.com/HiroNishikawa on twitter. I am sure he will be happy to answer your question.
Forum: Main CFD Forum December 14, 2020, 03:06
Replies: 6
Views: 962
Posted By praveen
Have you seen http://www.overtureframework.org ?

Have you seen http://www.overtureframework.org ?
Forum: Main CFD Forum November 10, 2020, 03:53
Replies: 12
Views: 3,170
Posted By praveen
agd gives good suggestion. I have always done it...

agd gives good suggestion. I have always done it like this. Makes the code more readable also. Declare floats as "real :: x", set values like

x = 1.0

Use sqrt (not dsqrt), etc.

Then while...
Forum: Main CFD Forum October 17, 2020, 01:35
Replies: 19
Views: 1,468
Posted By praveen
This is the right way. As you observed, the...

This is the right way. As you observed, the integrand is actually a linear function, so even a midpoint rule wrt \xi would be exact !!!
Forum: Main CFD Forum April 4, 2020, 02:22
Replies: 8
Views: 986
Posted By praveen
I see this trend of students posting HW on forums...

I see this trend of students posting HW on forums is increasing over time. We should not encourage this, but I dont know how to control it also. Sometimes it can be difficult to distinguish. I feel...
Forum: Main CFD Forum March 21, 2020, 02:16
Replies: 4
Views: 651
Posted By praveen
"spectral analysis of numerical schemes" seems to...

"spectral analysis of numerical schemes" seems to imply von-neumann analysis to study stability and dispersion/dissipation properties of the numerical scheme. Is this what you are asking ? If yes,...
Forum: Main CFD Forum March 18, 2020, 12:56
Replies: 19
Views: 981
Posted By praveen
The formula in the paper is only exact for an...

The formula in the paper is only exact for an affine function of the form

a + b x + c y

So it is not based on Simpson. There are many possibilities and its not obvious what the authors have...
Forum: Main CFD Forum March 18, 2020, 10:03
Replies: 19
Views: 981
Posted By praveen
The integral in the paper is over...

The integral in the paper is over [x_i-h/2,x_i+h/2] \times [y_j-h/2,y_j+h/2]. The answers given by other people here are taking the domain to be [x_i-h, x_i+h] \times [y_j-h,y_j+h]. Thats why you see...
Forum: Main CFD Forum March 14, 2020, 00:37
Replies: 5
Views: 820
Posted By praveen
In your case, most time is taken in solve phase....

In your case, most time is taken in solve phase. Your matrix is not that big so the direct solvers should be fine. Maybe this is normal. The solve phase will be the most expensive in such a method.
Forum: Main CFD Forum March 13, 2020, 23:53
Replies: 5
Views: 820
Posted By praveen
Matlab is slow if you use loops. If you cast...

Matlab is slow if you use loops. If you cast everything as matrix-vector operations it can do better.

For CFD, Matlab is not so great, ok for some initial learning, but you soon reach its...
Forum: Main CFD Forum January 30, 2020, 01:21
Replies: 23
Views: 2,953
Posted By praveen
If you reconstruct a unique value at each face...

If you reconstruct a unique value at each face (usually with a central stencil) then you use that to compute the flux. This would lead to central difference type schemes.

For convection dominated...
Forum: Main CFD Forum January 23, 2020, 03:02
Replies: 20
Views: 2,974
Posted By praveen
I improved my answer since it was not completely...

I improved my answer since it was not completely correct.

It seems common to use the phrase "symmetry bc" or "mirror bc" to refer to zero Neumann condition on some particular quantity, or even...
Forum: Main CFD Forum January 23, 2020, 00:14
Replies: 20
Views: 2,974
Posted By praveen
Slip bc means normal velocity is zero. ...

Slip bc means normal velocity is zero.

Symmetry bc means a lot more. You want to use symmetry conditions if your problem has some symmetry. E.g., if you want to solve flow around a cylinder,...
Showing results 1 to 25 of 340

 
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