High flow and pressure in peripheral reagion of Hele-Shaw cell

David_MicroFluidics · May 19, 2017, 09:07

Dear co-foamers,

I am using twoLiquidMixingFoam to simulate laminar, incompressible flow of two miscible liquids in a Hele-Shaw cell.
The cell is open on the edges (BC U: pressureinletOutletVelocity p: totalPressure) and has two connections close to the center with flow directions perpendicular to the orientation of the cell. The cell is filled with species A and species B is injected through on aperture and reaspirated at a higher flow rate through the second neighbouring aperture (BC U: fixedValue, p: fixedFluxPressure). Walls are walls (BC U: noSlip, p: fixedFluxPressure).

When simulating this, I nicely see the confinement of the injected species B and thigs in general look OK, but I get a max in flow and pressure in a region of my cell where actually nothing much happens and flow should be just radially directed inwards. Can anyone please give me a hint on what I might be doing wrong (the Mesh seems to be OK)? Thank you very much in advance!

Best regards,
David

HeleShawTrouble_David.jpg

MeshRect250_10.jpg

PS: one of the pioneering papers regarding this idea confining flows in such an arrangement, in case you are interested http://www.nature.com/nmat/journal/v.../nmat1435.html).

David_MicroFluidics · May 26, 2017, 10:04

Edit: solved the issue by going into fvSolution and switching from nOuterCorrectors = 0 to nOuterCorrectors = 50 (and implementing an abort condition when the residuals become smaller than a defined threshold, so that not all 50 iterations have to be made each cycle). If I understand correctly, with the previous setting I was running my PIMPLE solver in PISO mode, now it's true PIMPLE. Simulations are still running, but stuff looks promising. Fingers crossed

May 19, 2017, 09:07	High flow and pressure in peripheral reagion of Hele-Shaw cell	#1
David_MicroFluidics New Member David Taylor Join Date: Feb 2017 Location: Zürich Posts: 2 Rep Power: 0	Dear co-foamers, I am using twoLiquidMixingFoam to simulate laminar, incompressible flow of two miscible liquids in a Hele-Shaw cell. The cell is open on the edges (BC U: pressureinletOutletVelocity p: totalPressure) and has two connections close to the center with flow directions perpendicular to the orientation of the cell. The cell is filled with species A and species B is injected through on aperture and reaspirated at a higher flow rate through the second neighbouring aperture (BC U: fixedValue, p: fixedFluxPressure). Walls are walls (BC U: noSlip, p: fixedFluxPressure). When simulating this, I nicely see the confinement of the injected species B and thigs in general look OK, but I get a max in flow and pressure in a region of my cell where actually nothing much happens and flow should be just radially directed inwards. Can anyone please give me a hint on what I might be doing wrong (the Mesh seems to be OK)? Thank you very much in advance! Best regards, David HeleShawTrouble_David.jpg MeshRect250_10.jpg PS: one of the pioneering papers regarding this idea confining flows in such an arrangement, in case you are interested http://www.nature.com/nmat/journal/v.../nmat1435.html).

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May 26, 2017, 10:04		#2
David_MicroFluidics New Member David Taylor Join Date: Feb 2017 Location: Zürich Posts: 2 Rep Power: 0	Edit: solved the issue by going into fvSolution and switching from nOuterCorrectors = 0 to nOuterCorrectors = 50 (and implementing an abort condition when the residuals become smaller than a defined threshold, so that not all 50 iterations have to be made each cycle). If I understand correctly, with the previous setting I was running my PIMPLE solver in PISO mode, now it's true PIMPLE. Simulations are still running, but stuff looks promising. Fingers crossed