CFD Online Discussion Forums - [blockMesh] How can I define functions with m4?

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entropie

April 21, 2014 10:07

How can I define functions with m4?

Dear OF-Users,

I'm trying to create a blockMeshDict with m4. I need to define all coordinates on the Z-axis as functions of coordinates on the X-axis. So far my m4-code looks like this:

define (x1, 7)
define (x2, 5)
...
define (x20, 4)

define (z1, calc(x1*2+1))
define (z2, calc(x2*2+1))
...
define (z20, calc(x20*2+1))
etc.

And the problem is, I have about 100 coordinates and it is a bit awkward to define all 100 coordinates one by one.

Maybe can somebody tell me how can I just once define a function for all Z-coordinates, if it's possible?

Best regards,
Olivia

cutter

August 13, 2014 09:38

Hi,

you could use any scripting or programming language to write the contents of the blockMeshDict.

For example the following Python script

Code:

#!/usr/bin/env python





def func(x):

    return x*2.+1.





def main():

    for i in range(0, 11):

        x = .1*i

        z = func(x)

        print 'x{} {};'.format(i,x)

        print 'z{} {};'.format(i,z)





if __name__ == "__main__":

    main()

would result in

Code:

Cutter

cutter

August 13, 2014 10:00

The above post was just a workaround for your problem. Regarding your initial question on m4, maybe the following link helps:

http://www.slac.stanford.edu/comp/un...nfo/m4_11.html

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