how do i use WINISD for an openbaffle subwoofer design

hello DIYAUDIO, sorry for my English, I will do my best to be clear.

I have a nice open baffle that I built from a GRS 8SW-4. it's good, I like it very much I think it go down to 50-55 HZ.... I never measured its performance. I use it to help my DML speakers get a full range sound. the system is amplified by a small TPA3116D2 amp (AIYIMA A03) and the bass freq is set to about 200 HZ the (knob can go from 40-250HZ)

Now I'm building a new setup of 2.1 and will like to use WINISD these time, using a pair of full range Dayton audio RS100 4 and my good old GRS 8SW-4 open baffle subwoofer. my question is how do I set the open baffle in WINISD? I trayed setting it up as a 99999 liter box and a 100X100CM port 🙂 dose it make sense ?... probably not.... can you advise?
I set a low pass of 100 HZ on the sub and a high pass of 100HZ on the RS100 to simulate the amplifier bass freq knob at 100HZ, is that right to do?


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Setting a very large closed box is correct as far as driver impedance, cone excursion, however the SPL in this simulation is representing an infinite baffle result, not the open baffle.

I don't think it can be easily done from WinISD, but can be done within VituixCAD, at least for flat baffles. For H or U frames it gets more complex, as these are truly transmission line enclosures and not easily modelled in either WinISD or VituixCAD.

In VituixCAD, open the diffraction tool, model the flat baffle, make sure "open baffle" is checked, then export the result. Now, model the enclosure as "infinite baffle" in the enclosure tool, or closed box with very large volume. Under the align tab, at the bottom you will find a selection for diffraction response. Load the diffraction response and check the box to enable it.