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Your file has the microfluidics module present. A lot of people may not have this module and will get a license error trying to openg it (I did). If you can, just post the file geometry w/o any phsyics.

I have the same problem. Did anyone manage to fix this? Have 4 lines (1 parametric curve & 3 straight lines) which I've connected using a Union. However, I can't convert this figure into a solid. Right now it's just an outline. Here's a copy of my file. I don't have a microfluids module so it shouldn't have the license error issue that the other file had.

Hi

Try the "Geometry - right click - Conversions - Convert to Solid".

By the way you do not need the union in this case, so long the loop is closed its OK

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Good luck
Ivar

I've been trying to do this too with lines and curves, and the convert to solid doesn't seem to do much. I was able to get a solid using parametric curves and open polygons (instead of lines). That may help.

Hi !
i'm trying to convert a surface geometry to a solid (Geometry - right click - Conversions - Convert to Solid) and every time the following message appear :

"The operation resulted in an empty geometry."

i want to understand why this message appear; please help me to find a solution to this problem.

Best regards

Hi all,

Here is some information and tips for converting nonsolid geometries to solids.

Firstly, a surface cannot be converted to a solid unless it is a closed solid; otherwise, that operation results in an empty geometry.

Also, you cannot convert curves or lines in 3D into a solid directly, but if the curves or lines form a closed curve and that curve lie in a plane, then you can form a surface that you can extrude into a 3D solid. To do so, add a work plane in the same plane as the closed curve, and then, under the Plane Geometry node, add a Cross Section node to make the closed curve appear as a closed curve in the 2D Plane Geometry, where you can then use a Convert to Solid node to convert it into a 2D solid (that is, a 3D surface).

A nonclosed 2D surface can be converted to a solid using extrusion so that it gets a nonzero thickness. With the Design Module, there is also a Thicken feature that can thicken a surface into a (thin) solid.

The problem in the parametric_surface geometry is that the topology is invalid (due to self-intersecting curves). If you use two Parametric Surface nodes instead, with the same settings except that in the first one, the s1 parameter runs from 0 to pi, and in the other, it runs from pi to 2*pi (instead of one parametric surface where s1 runs the full circle from 0 to 2*pi). With that modification, and an active work plane with the bottom surface, you can form a 3D solid using a Convert to Solid node with all three surfaces as the input. With the CAD Import Module, you can use a Cap Faces feature to create a closed surface instead of creating a closing bottom surface in a work plane.

For the TopoBoundary model, the closed 2D curve can be directly converted to a 2D solid using a Convert to Solid node in the latest version of COMSOL Multiphysics, version 5.2a, as well as in version 5.2.

Best regards,
Magnus Ringh, COMSOL