I suspect the flow isn't doing much so the Accuracy Controls are kicking in to save cpu https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v231/en/flu_ug/flu_ug_sec_discrete_use_oview.html%23flu_ug_sec_pt_numerics
Note, 1 micron particles will probably follow the flow so may well miss the screens. How big are the holes, and how large is the near wall cell?
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