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Is there code to plot stream function from u & v velocities

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Old   August 1, 2017, 07:11
Default Is there code to plot stream function from u & v velocities
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Hello I am searching for a code can plot stream function in terms of u & v velocity components? May somebody guide me to a similar code?

Thanks
Khalid
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Old   August 5, 2017, 11:17
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Hi Kbaker,

Here is a piece of code in fortran to compute the stream function from the longitudinal U componnent of the velocity field.
Let me know if you need further details.

Leflix


C************************************************* *********
SUBROUTINE STREAM (U, DY, NI, NJ, PSI)
C************************************************* *********

IMPLICIT NONE

INTEGER NI,NJ, KX,KY, I, J
PARAMETER(KX=512,KY=512)

REAL*8 U, DY,PSI


DIMENSION U(0:KX,0:KY), PSI(0:KX,0:KY)

DO I=0,NI

PSI(I,0)=0.d0

DO J=1,NJ
PSI(I,J)= PSI(I,J-1) + U(I,J)*DY
END DO

END DO

RETURN
END
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Old   August 5, 2017, 12:16
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Thanks Leflix for the reply. Actually I not looking for a fortran program I want to draw the stream function in Tecplot code? Do you have experience with it?

Khalid

Quote:
Originally Posted by leflix View Post
Hi Kbaker,

Here is a piece of code in fortran to compute the stream function from the longitudinal U componnent of the velocity field.
Let me know if you need further details.

Leflix


C************************************************* *********
SUBROUTINE STREAM (U, DY, NI, NJ, PSI)
C************************************************* *********

IMPLICIT NONE

INTEGER NI,NJ, KX,KY, I, J
PARAMETER(KX=512,KY=512)

REAL*8 U, DY,PSI


DIMENSION U(0:KX,0:KY), PSI(0:KX,0:KY)

DO I=0,NI

PSI(I,0)=0.d0

DO J=1,NJ
PSI(I,J)= PSI(I,J-1) + U(I,J)*DY
END DO

END DO

RETURN
END
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Old   August 5, 2017, 12:21
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That shoud be part of tecplot already... at least I recall it was. You should read the manual if that feature is not particularly immediate to reach.
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Old   August 5, 2017, 12:26
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It is very easy, you have just to activate it in the menu and then click on a point in the field to have one streamline.

http://www.tecplot.com/blog/2014/10/...article-paths/
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Old   August 5, 2017, 15:16
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Ok ! Yes you have to upload your velocity field in 4 columns
x y Ux Uy
................
................

Then you activate streamtrace and as Filipo mentioned it click on a point you will have a streamline there. Yiu can also trace a line along the two opoosite corner of your domain and it will display sveral streamlines. Check out the documentation of tecplot.

Leflix
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Old   August 5, 2017, 16:44
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Attachment 57592Thanks leflix and Filippo for the information. Leflix I already did a file with four coloums i.e. x y u v I saved it as general text file when I open it in Tecplot as a text and in order to activate streamtraces I need to do triangulation. The problem when I attempt to do 2D triangulation it give me error as the attached pict? so what the problem ?

Khalid
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Old   August 5, 2017, 16:56
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Is your grid structured or unstructured ?
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Old   August 5, 2017, 17:04
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I have same problem

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Originally Posted by leflix View Post
Is your grid structured or unstructured ?
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Old   August 5, 2017, 17:08
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Its structured grid I use meshing code to make the mesh and solve the problem using CFX code. My geometry is a sqaure cavity.

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Is your grid structured or unstructured ?
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Old   August 5, 2017, 17:12
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Check first if the data are loaded correctly and show the grid to see if it appears structured
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Old   August 5, 2017, 17:13
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so you don't need to make a triangulation. Check how to format the data for structured grid. You have to loop on j and i , the number of nodes in j direction is NJ, and NI the number of nodes in the i direction.

write(1,*)'zone i=',NI,', j=', NJ,', F=POINT'

do j=1,NJ
do i=1,NI
write(1,*) Xc(i,j), Yc(i,j), U(I,J), V(I,J)
end do
end do
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Old   August 5, 2017, 17:15
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leflix is correct, the first line is the header, the you can activate directly the streamtracer without triangulation
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Old   August 5, 2017, 17:23
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I am really not sure about the type of mesh structured or not? I uploaded some picts for it?


Quote:
Originally Posted by leflix View Post
so you don't need to make a triangulation. Check how to format the data for structured grid. You have to loop on j and i , the number of nodes in j direction is NJ, and NI the number of nodes in the i direction.

write(1,*)'zone i=',NI,', j=', NJ,', F=POINT'

do j=1,NJ
do i=1,NI
write(1,*) Xc(i,j), Yc(i,j), U(I,J), V(I,J)
end do
end do
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File Type: jpg 1.jpg (181.5 KB, 7 views)
File Type: jpg 2.jpg (141.9 KB, 6 views)
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Old   August 5, 2017, 18:22
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It is definetely a structured grid. You can access to every nodes with 2 indices i and j.

Leflix
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Old   August 6, 2017, 02:13
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Dear Leflix As I think the part of program you sent it is in Fortran? right? I need to ask in order to apply it to the data I need to save the data in a file then call it by open? my question is do I need separate file for x,y,u and v or I store all of it in one file (as I stored it now see attached dat file which I arrange starting from left x,y,u,v)?
What part of program should be written before this statement:

write(1,*)'zone i=',NI,', j=', NJ,', F=POINT'



Quote:
Originally Posted by leflix View Post
It is definetely a structured grid. You can access to every nodes with 2 indices i and j.

Leflix
Attached Files
File Type: txt stream.txt (171.3 KB, 5 views)

Last edited by kbaker; August 6, 2017 at 04:53.
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Old   August 6, 2017, 07:20
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Hi Kbaker,

You should write all the data in the same file
x, y, U, V

just at the begining of the file write this:
VARIABLES= "X","Y", "U","V"
zone i= 100, j= 100 , F=POINT

assuming you have 100 grid nodes in i direction and 100 grid nodes in j direction. (this should be automatized when generatin the file in your code)

and then write
x,y, U,V as you did in your file.

name the file with .plt as extension rather than .txt so that Tecplot can recognise it and open it directly. Name it velocity.plt seems not bad.
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Old   August 6, 2017, 07:51
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Is this code need to be programed in Fortran language?
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Old   August 6, 2017, 07:57
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I am really confused about the program. Now I am started with writing a program to just reading the variable in a one matrix and print it as below:

IMPLICIT none
real X
integer i,j
DIMENSION X(5000,4)
open (unit = 1, file = "f:\velo.txt")
open(unit = 2 , file = "d:\fortran programing\res1.txt")
do i=1,4624
do j=1,4
Read(1,*) X(I,J)
enddo
enddo
do i=1,4624
write(2,*) (X(I,j),j=1,4)
enddo
stop
end



I just want to test the program validity in printing the variables but it tell me error: run time error F6501: Read(F:\velo.txt)
-end of file encountered

What the problem with my data? I attached the dat file?

Quote:
Originally Posted by leflix View Post
Hi Kbaker,

You should write all the data in the same file
x, y, U, V

just at the begining of the file write this:
VARIABLES= "X","Y", "U","V"
zone i= 100, j= 100 , F=POINT

assuming you have 100 grid nodes in i direction and 100 grid nodes in j direction. (this should be automatized when generatin the file in your code)

and then write
x,y, U,V as you did in your file.

name the file with .plt as extension rather than .txt so that Tecplot can recognise it and open it directly. Name it velocity.plt seems not bad.
Attached Files
File Type: txt velo.txt (171.3 KB, 1 views)
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Old   August 6, 2017, 08:06
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First how many points do you have in x direction (i) and in y direction (j) ?
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