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June 30, 2009, 19:21 |
creating a field function
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#1 |
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Hello,
I am working on a project where I have to simulate the flow of air through a pipeline. I want to create the velocity inlet profile on star ccm+. How do I implement this function into the program. funktion : -2E-08z^4 + 2E-05z^3 - 0,007z^2 + 1,03z- 4,578 Thanks in advance. Can Last edited by can_yas; July 1, 2009 at 03:26. |
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July 1, 2009, 05:37 |
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#2 |
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(-2*pow(10,8)*(pow($$Centroid[2],4))) + (2*pow(10,5)*(pow($$Centroid[2],3))) - (0.007*(pow($$Centroid[2],2))) + (1.03*($$Centroid[2])) - 4.578
In the above formulation you can also use $$Position[2] instead of $$Centroid[2] is thats what you need. To implement the field function on the boundary Region > Boundaries> Physics Values > Velocity Magnitude (Method > field function) Last edited by SKK; July 1, 2009 at 06:58. |
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July 1, 2009, 06:59 |
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#3 |
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(-2 * Pow (10.8) * (pow ($ $ Centroid [2], 4))) + (2 * pow (10.5) * (pow ($ $ Centroid [2], 3))) - (0.007 * (pow ($ $ Centroid [2], 2))) + (1.03 * (pow ($ $ Centroid [2], 1))) - 4.578
I have the equation changed(red color), ist dies correct? and if I have this equation enter into the program, I get error message "Compiled field function type is not vector " Thanks in advance. Can |
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July 1, 2009, 07:06 |
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#4 | |
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Quote:
(-2 * pow (10,8) * (pow ($$ Centroid [2], 4))) + (2 * pow (10,5) * (pow ($$ Centroid [2], 3))) - (0.007 * (pow ($$ Centroid [2], 2))) + (1.03 * ($$ Centroid [2])) - 4.578 In the pow command variables are separated with commas. Also, no space between the two $$ signs. |
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July 1, 2009, 07:41 |
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#5 |
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Thank you for your effort, unfortunately, does not again.diese equation is a velocity distribution in a Pipe.
I have descriped cylindrical coordinatesystem in the Inlet .it must be the Origin in the middle? Part(Pipe) has a symmetry Plane Last edited by can_yas; July 1, 2009 at 09:03. |
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July 1, 2009, 08:30 |
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#6 |
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Sure that he need to write the E8 as a pow?
Normally it works without this fine?! |
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July 1, 2009, 08:53 |
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#7 |
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Hi,
I have changed the equation again. -0.00000002 * (pow ($$ Centroid [2], 4)) + 0.00002 * (pow ($$ Centroid [2], 3)) - 0.007 *(pow($$ Centroid [2], 2)) + 1.03 * ($$ Centroid [2]) - 4.578 Unfortunately, I get the same error message again,"Compiled field function type is not vector " Thanks |
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July 1, 2009, 09:01 |
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#8 |
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Have you changed the field function 'Type' to vector?
I don't get this error message. I am using an older version of STAR CCM+. I will check it with the new version later and let you know. |
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July 1, 2009, 09:02 |
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#9 |
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Hmm is the function set a scalar?
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July 1, 2009, 09:18 |
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#10 |
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No, I have field function 'Type' Scalar. I am using version 4.2 of STAR CCM+. how did they coordinate system defined?
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July 1, 2009, 09:23 |
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#11 |
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for vector definition, the three velocity components are described [x,y,z]. I guess in your case it would be
[0,0,-0.00000002 * (pow ($$ Centroid [2], 4)) + 0.00002 * (pow ($$ Centroid [2], 3)) - 0.007 *(pow($$ Centroid [2], 2)) + 1.03 * ($$ Centroid [2]) - 4.578] |
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July 1, 2009, 09:27 |
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#12 |
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4.2? You mean 4.02?
In the properties you have the function type. Make a screenshot. |
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July 1, 2009, 09:32 |
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#13 |
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July 1, 2009, 09:39 |
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#14 | |
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Quote:
That is really unbelievable. This works. I am very grateful for their help |
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July 1, 2009, 09:41 |
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#15 |
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July 1, 2009, 10:11 |
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#16 |
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@SKK: Maybe you should make a benchmark for this extra pow function
A other way would be to use $Centroid_i (maybe a "cleaner" way). Of cource you need the vector "style" for the velocity I make too much 2D |
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November 26, 2020, 08:37 |
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#17 |
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jas
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I want to do what OP did but with a parabolic velocity profile inlet. The eqaution would be
v(r) = Vm(1-(r^2/R^2)). What code would i have to implement. thanks |
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November 26, 2020, 15:40 |
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#18 |
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Chaotic Water
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November 27, 2020, 10:08 |
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#19 | |
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Madrigal
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Quote:
Use this: ${Vm} * (1-(pow(${RadialCoordinate},2)/pow(${Radius},2))) CFD2DXY |
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November 27, 2020, 10:18 |
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#20 | |
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jas
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Quote:
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