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Pressure constraint in laminar flow

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Hi all,

I'm trying to model dilute transport of a chemical species in laminar pipe flow. However, I keep getting the following error message:

"There is no feature constraining the pressure. A pressure constraint is required to specify the pressure level. Ignore this warning if the pressure is constrained using pointwise or weak constraints. - Node: Laminar Flow (spf)"

I specified the pressures at the inlet and outlet of the horizontal cylinder. Head loss is negligible. I've attached a zip file containing my simulation. Any and all help would be appreciated! Thank you



2 Replies Last Post Jan 31, 2023, 10:01 a.m. EST
Dave Greve Certified Consultant

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Posted: 1 year ago Jan 19, 2023, 12:08 p.m. EST

I'm not sure what is going on in this model, in particular I don't understand the Symmetry boundary selections.

However- laminar flow problems usually require a Pressure Point Constraint at one point in the geometry. Also try Fully Coupled for the solver.

I'm not sure what is going on in this model, in particular I don't understand the Symmetry boundary selections. However- laminar flow problems usually require a Pressure Point Constraint at one point in the geometry. Also try Fully Coupled for the solver.

Dmitry COMSOL Employee

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Posted: 1 year ago Jan 31, 2023, 10:01 a.m. EST

HI!

I specified the pressures at the inlet and outlet of the horizontal cylinder.

Yes, but these boundary conditions are overrided with Symmetry node, that is used for all external boundaries, that's why there is no pressure constraint in the model.

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Best regards,
Dmitry Lazarev
HI! >I specified the pressures at the inlet and outlet of the horizontal cylinder. Yes, but these boundary conditions are overrided with *Symmetry* node, that is used for all external boundaries, that's why there is no pressure constraint in the model.

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