Bagel Mode is where there is no power in the core of the beam and is made by mixing Tem10 and Tem01. Does anyone know a way to do this without mixing modes? I need to do this with acoustics as a set of standing waves for a particle trap in a moving fluid system. I want sizes not desired to pass through the core but those in the size fraction select to get trapped. I then plan to slightly change the beat and move them down the fluid to a collection pick off. I know how to do this in a static system but need it in a flowing system. Still low Reynolds numbers relatively slow flow. A sort of modified stokes trap. I am aware of the cell sorter methods. That’s not what I’m after. Looking at around 2-10mhz ultrasonics. Thinking to do this by setting up a standing wave interference between two or more sources. Just not sure how to make the 3d structure with superposition. Think of a bagel rolling inside out like a solid rubber tire making a zone of pressure that selects and traps particles. Now that moves like a belt through the system. Just how to make such a construct? The math for the selective trapping I already know regarding shear and induced drag. That’s sound physics and in use in many industries. Just how to form the standing wave in bagel mode and move it spatially is unknown. I’m only trying to do this in a 1/4” dia pipe so the system need not be very powerful. If I can make it work I might try other modes for mixing. Application at moment is sla resin cleaning. Having issues regular filtering can’t seem to solve with partially cured resin that spoils the parts. Want to actively filter the resin and keep it mixed while sitting in the tray. Physical particles removal won’t work as there is a desired particle and an undesired. Might also apply to dye lasers.