Discussion Forum

Posted: 1 decade ago 02.02.2010, 16:55 GMT-5

I've had to do similar things. My own approach has been to export the 2D slice data to Matlab and do the plotting that I want there. But I'd also be interested to know if there is an easy way to do it directly within Comsol Multiphysics.

Posted: 1 decade ago 03.02.2010, 02:00 GMT-5

Hi I mostly create interiour boundaries to use them as "metrology" support, but to get your "height data" approach in 3D, I can only think of one way within COMSOL (

Posted: 1 decade ago 10.02.2010, 11:48 GMT-5

Good day and many thanks to Robert, Ivar, and Rune for their contributions to this question. Rune Westin at COMSOL Support provided some needed detail which I’ll include along with my embellishments. Rune has also provided the very useful model file which is attached. (extrusion_demo.mph) Again the objective is to create a 3D surface plot of a parameter such as pressure or stress acting on a particular boundary plane within the model. This is readily done in 2D simulations with the Post Processing/Plot Parameters/Surface GUI. Here the Height Data tab controls the 3D presentation. To accomplish the task in a 3D simulation the parameter data from the plane of interest in the 3D model is ‘Extruded’ onto a 2D polygon using a work plane. It is this extruded data that is then plotted into the 3D Surface using the same GUI mentioned above. Now some detail applicable to 3.5a. As Ivar suggests one may create the model and add a ‘metrology’ source plane (boundary) at the location of interest. (This will be in the 3D, Geom1 environment.) It may be useful to complete the model and test it at this juncture. To prepare for the extrusion data a ‘destination’ 2D region will be required. First create a work plane, Draw/Work-Plane Settings/Face Parallel, which will reside in Geom2. In Geom2 create a polygon of the same shape and dimension as the source metrology plane in Geom1. Mapping the data from the 3D source (Geom1) to the 2D destination (Geom2) is accomplished with an Extrusion Coupling Variable. While in tab Geom1, use Options/Extrusion Coupling Variable/Boundary Variables to open the Boundary Extrusion Variables GUI. On the Source tab select the metrology boundary which has been added. Assign a meaningful name and include an expression. The expression may be an existing Application Mode variable such as ‘p’ or ‘sz_smsld’. On the Destination tab select the Geometry to be *Geom2 and enter the Variable name you just applied in the Source tab. You will notice that the Geom2 tab is now active to enable the select the destination polygon (2D Subdomain selection) created earlier for this purpose. Then with the Source Vertices tab and the Destination Vertices tabs establish a one-to-one correlation for the mapping. The sequence is important. There may be a trick, but it seemed necessary to run the simulation again with the Geom2 tab active. Once complete the desired plot can be obtained just as with the 2D model. Still in the Geom2 tab select PostProcessing/Plot Parameters/Surface. On the Surface Data tab the Expression will be the extrusion variable name assigned earlier. Plotting at this point will provide 2D plot but if the Height Data tab is selected and the same variable name entered as the Expression there one will obtain a 3D surface plot as desired. Rune offered these documentation reference points which I’ll pass along. Comsol MultiPhysics User’s Guide: Chapter 2: Geometry Modeling and CAD Tools Page 59 in Creating a 3D Geometry Model find Creating and Using 2D Work Planes Comsol MultiPhysics User’s Guide: Chapter 4: Modeling Physics and Equations Page 275 in Using Coupling Variables find Extrusion Coupling Variables. Again many thanks to the community. Marty Key Words: 3D surface plot, contour plot, extrusion

Attachments:

• extrusion_demo.mph

Posted: 1 decade ago 27.02.2010, 04:55 GMT-5

Hi Marty Thanks for the precise description, such info is very usefull, as complements to the documentations Havn't been on the forum for some time, stuck on a difficult simulation and design case, therefore my late reply ;) Have a nice day Ivar

Posted: 1 decade ago 24.08.2010, 11:03 GMT-4

Hi Robert, I am interested in the post you have about how you went about rendering a 3D surface plot from the 2D slice you exported from COMSOL. I need to do the same thing. I have flow through a tube, with obstacles in the flow. I would like to create a 3D velocity profile plot after the obstacles. I have 2D slices of the velocity profiles, and I have been trying to import them into MATLAB, and create a surface plot based on the color, but I am not completely succesful. I was wondering if you had any tips. Thanks, -Alex

Posted: 1 decade ago 21.06.2011, 07:59 GMT-4

Hi there I am stuck with this 2D versus 3D thing. I extruded a 3D geometry onto a 2D geometry by 'work plane' method. I then drew a circle on this 2D geometry. When I clicked on any physics and tried to assign a boundary condition to the circle, I did not see the circle as a surface on the 3D geometry. Did I miss some steps in between? I am using 4.0 by the way. Hope you may help. Thanks! liwah [QUOTE] Good day and many thanks to Robert, Ivar, and Rune for their contributions to this question. Rune Westin at COMSOL Support provided some needed detail which I’ll include along with my embellishments. Rune has also provided the very useful model file which is attached. (extrusion_demo.mph) Again the objective is to create a 3D surface plot of a parameter such as pressure or stress acting on a particular boundary plane within the model. This is readily done in 2D simulations with the Post Processing/Plot Parameters/Surface GUI. Here the Height Data tab controls the 3D presentation. To accomplish the task in a 3D simulation the parameter data from the plane of interest in the 3D model is ‘Extruded’ onto a 2D polygon using a work plane. It is this extruded data that is then plotted into the 3D Surface using the same GUI mentioned above. Now some detail applicable to 3.5a. As Ivar suggests one may create the model and add a ‘metrology’ source plane (boundary) at the location of interest. (This will be in the 3D, Geom1 environment.) It may be useful to complete the model and test it at this juncture. To prepare for the extrusion data a ‘destination’ 2D region will be required. First create a work plane, Draw/Work-Plane Settings/Face Parallel, which will reside in Geom2. In Geom2 create a polygon of the same shape and dimension as the source metrology plane in Geom1. Mapping the data from the 3D source (Geom1) to the 2D destination (Geom2) is accomplished with an Extrusion Coupling Variable. While in tab Geom1, use Options/Extrusion Coupling Variable/Boundary Variables to open the Boundary Extrusion Variables GUI. On the Source tab select the metrology boundary which has been added. Assign a meaningful name and include an expression. The expression may be an existing Application Mode variable such as ‘p’ or ‘sz_smsld’. On the Destination tab select the Geometry to be *Geom2 and enter the Variable name you just applied in the Source tab. You will notice that the Geom2 tab is now active to enable the select the destination polygon (2D Subdomain selection) created earlier for this purpose. Then with the Source Vertices tab and the Destination Vertices tabs establish a one-to-one correlation for the mapping. The sequence is important. There may be a trick, but it seemed necessary to run the simulation again with the Geom2 tab active. Once complete the desired plot can be obtained just as with the 2D model. Still in the Geom2 tab select PostProcessing/Plot Parameters/Surface. On the Surface Data tab the Expression will be the extrusion variable name assigned earlier. Plotting at this point will provide 2D plot but if the Height Data tab is selected and the same variable name entered as the Expression there one will obtain a 3D surface plot as desired. Rune offered these documentation reference points which I’ll pass along. Comsol MultiPhysics User’s Guide: Chapter 2: Geometry Modeling and CAD Tools Page 59 in Creating a 3D Geometry Model find Creating and Using 2D Work Planes Comsol MultiPhysics User’s Guide: Chapter 4: Modeling Physics and Equations Page 275 in Using Coupling Variables find Extrusion Coupling Variables. Again many thanks to the community. Marty Key Words: 3D surface plot, contour plot, extrusion [/QUOTE]

Posted: 1 decade ago 24.02.2014, 09:57 GMT-5

Hello, I would like to export data from 2D surface plot. I did right click the surface plot and saved it as data and exported it. Let say for the geometry one edge is from 1 to m and other edge is from 1 to n and the color data has to have m x n elements. However the exported color data dimension is same as m and n. There is smth wrong. Could someone help me please? I used 4.3b. I need to export all data points as I would like to use MATLAB for further data processing. Thank you regards Sel