How important is the actual shape? The "circular" part of it is not really circular, so [for example] a Polyline with line segments at both ends and an arc segment between them, and with width, can't duplicate that shape very accurately. And it wouldn't be able to do the intersections of the line and arc segments the way they're shown. Here, the left one has a single arc segment making the curve, and the right one has three tangent arc segments. Closer, but still not the right configuration at the "knees."
But here, on the left is MTEXT in which I used an Omega character [slightly different shape from yours, but if you have the font you used...] in the chart called up by the Symbol option in the Text-editing ribbon, and made it Bold. TXTEXP produced the two-outlines version in the middle, then a TRIM command removed the coinciding horizontals at the joint between outlines, and JOIN made it all into one Polyline outline on the right.
Kent Cooper, AIA 
another way is to type character map in your search window look for the symbol and copy and paste it in your autocad drawing, if necessary you can explode and scale to suit your needs. thanks
@Kent1Cooper wrote:
.... TXTEXP produced the two-outlines version in the middle, then a TRIM command removed the coinciding horizontals at the joint between outlines, and JOIN made it all into one Polyline outline on the right.
I don't know anything about COMSOL, so maybe this doesn't matter, but the result of that procedure is a Polyline using short line segments to make the "curved" parts. If it needs to have real curvature, it can be made into a Spline instead. Break it at the joints between straight and curved parts, use PEDIT to apply Spline curvature to the curved parts, then use SPLINEDIT to Join them all together [the straight parts will remain straight, even though part of a Spline].
Kent Cooper, AIA
Since COSMOL can work with NURBS splines as noted here, I would create the shape with splines rather than a polyline with a lot of short segments.
I would start by creating a few reference lines for the vertical line of symmetry, and horizontal lines at the top of the two curves to be used to define the horizontal slope of the spline at those points. Use a polyline for the straight segments (green) and 4 or 5 fit points for the curves (cyan). The fit points I used are the blue grips you see highlighted. Use the T (tangency) option for the end of the spline and use osnap nearest to ensure the slop is horizontal. Do not worry at this stage that the spline does not perfectly match the desired shappe.
Now select the spline a zoom into the area that does not have a good match and in the properties box change the Method from Fit to Control Vertices and the spline will show its CV points.
Click and drag a CV to get a better match. Below I've moved the 2nd CV.
Edit the spline CVs as necessary and then mirror the splines and polyline. Keep in mind that you get smoother curves with as few CV's as possible but if you need more local control of the spline's shape feel free to add additional CV's with the splinedit command. You should find that you can get a pretty good fit in a few minutes. Finish by using splinedit to join all the splines and polylines into one spline.