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-   -   How to input the wall temperature b.c.? (https://www.cfd-online.com/Forums/cd-adapco/56498-how-input-wall-temperature-b-c.html)

 Jimmy March 7, 2008 15:14

How to input the wall temperature b.c.?

Anton, sorry I start this new message for the same topic.

The wall temperature data are as follows:

X Y Z Wall Temperature 49.79 223.25 -112.42 507.33 47.82 230.65 -133.58 484.47 54.05 228.31 -109.53 492.75 55.76 227.48 -115.26 483.30 42.13 228.70 -133.03 496.40 43.86 225.80 -130.58 494.14 39.81 230.16 -131.58 503.69 47.91 228.30 -112.44 506.67 57.91 229.08 -113.01 484.75 .........

Here X, Y and Z are the coordinates of the measurement points on the surface. Totaly we have more than 100,000 measurement points.

From my understanding, there might be two approaches:

(1) Wall temperature table: I don't know how to set a table for above wall temperature conditions, because these points are located on a 3D surface, not a 2D surface.

(2) User subroutine bcdefw.f: This needs to map the measured temperatures to the surface mesh of Star-CD model. But I don't have a tool to do the mapping for this purpose.

Jimmy

 Jimmy March 7, 2008 15:18

Re: How to input the wall temperature b.c.?

The coordinates and wall temperatures measured on the surface are as follows:

X Y Z Wall Temperature 49.79 223.25 -112.42 507.33 47.82 230.65 -133.58 484.47 54.05 228.31 -109.53 492.75 55.76 227.48 -115.26 483.30 42.13 228.70 -133.03 496.40 43.86 225.80 -130.58 494.14 39.81 230.16 -131.58 503.69 47.91 228.30 -112.44 506.67 57.91 229.08 -113.01 484.75 .........

Sorry for the mess with the first message.

Jimmy

 James March 8, 2008 10:20

Re: How to input the wall temperature b.c.?

You can PMAP as well

Create a mesh with the measured data points as the vertices.

Put a shell on your model surface

Read in the measured data surface and data into Prostar

VAVE the read in shells to get cell data.

PMAP the data

Write out the model surface mesh and data

Write a 6 line program to create a file containing the boundary elements and define one region per boundary

 Anton Lyaskin March 11, 2008 06:36

Re: How to input the wall temperature b.c.?

Ok, so as far as I see, it's more like a cloud of points than regular 3D grid, right? I meen, every value for any coordinate appears only once (you can check it by sorting the data on X, Y and Z)? Then the first idea I have is to write table header like INDEPENDENT X, <Number of point you have>, Y, <Number of point you have>, Z, 0 and try to feed it to ProSTAR. You'll probably have to increase MXSTOR parameter above of the default 200000 value to something like <number of points>*4

 Anton Lyaskin March 11, 2008 06:38

Re: How to input the wall temperature b.c.?

Sorry, I've messed with the brackets

INDEPENDENT X, number_of_points, Y, number_of_point, Z, 0

and MXSTOR is number_of_points*4

 Jimmy March 11, 2008 08:52

Re: How to input the wall temperature b.c.?

Hi James,

It looks like this will be quite a lot of work. Previously I used Fluent for this purpose, and it seems much easier.

Now the problem is, how to create the surface mesh from the measured data?

Thanks,

Jimmy

 Jimmy March 11, 2008 09:39

Re: How to input the wall temperature b.c.?

Anton, your method could be more convenient. Here I want to describe the measured data again because the previous post was messed up for some reason:

X Y Z Wall temperature

49.79 223.25 -112.42 507.33

47.82 230.65 -133.58 484.47

54.05 228.31 -109.53 492.75

55.76 227.48 -115.26 483.30

42.13 228.70 -133.03 496.40

43.86 225.80 -130.58 494.14

......

Totally we have 20,000 measurement points which is cooresponding to 20,000 X, Y and Z numbers shown above. Here my quesitons are:

(1) From my understanding, the "number of points" in your message should be 20,000 which is the number of measurement points. Is is right?

(2) Is there any special requirement with the X, Y, Z and Temperature format in the table file?

Thank you very much,

Jimmy

 Anton Lyaskin March 11, 2008 15:41

Re: How to input the wall temperature b.c.?

(1) Yes, 20000 (2) No, it is said that they can have free format. They can even go unsorted.

Looking forward to see whether this will work or not :)

 Jimmy March 11, 2008 16:58

Re: How to input the wall temperature b.c.?

Anton, I created the table as mentioned before. It seems that Star-CD requires to read in totally 20,000 x 20,000 x 1 (nx=20000, ny=20000, nz=1), but not 20,000 points from the table. It looks like that this table format is still for the volume-distributed points, but not surface-distributed points which is what I want.

Any suggestions?

Jimmy

 Anton Lyaskin March 14, 2008 10:31

Re: How to input the wall temperature b.c.?

Well, I've checked it too and looks you're right. That meens that you'll have to go for user subroutine. And you'll need to code some mapping algorithm into it, like 1) reading coordinates of the boundary, 2) looking for the nearest data points in your data file, 3) somehow interpolating your data to boundary location. And because your data points are scattered, this can be a real pain!

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