[Nek5000-users] v17.0 vs v17.0.0.beta2 regarding Stress Formulation and Pn/Pn-2

Tue Feb 13 10:46:53 CST 2018

Jean,

I think what you want to do is to map the pressure on the velocity mesh. There is thread that explains how to do that:
https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2010-July/000767.html

Since the pressure is discontinuous I am not sure the pressure field will be smooth on the velocity mesh, though.

Marco

From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of "nek5000-users at lists.mcs.anl.gov" <nek5000-users at lists.mcs.anl.gov>
Reply-To: "nek5000-users at lists.mcs.anl.gov" <nek5000-users at lists.mcs.anl.gov>
Date: Tuesday, February 13, 2018 at 10:54 AM
To: nek5000-users <nek5000-users at lists.mcs.anl.gov>
Subject: [Nek5000-users] v17.0 vs v17.0.0.beta2 regarding Stress Formulation and Pn/Pn-2

Dear All,

I am using mixed 'W   ' and 'SYM' boundary conditions on a boundary that is not aligned with x,y,z axes. (with IFSTRS=T)

When using the previous v17.0.0.beta2 version, I could use these mixed boundary conditions with the Pn/Pn pressure formulation, giving a continuous pressure field.

After upgrading to v17.0, I get a number of the following runtime errors when using Pn/Pn:

---
Mixed B.C. on a side nonaligned with either the X,Y, or Z axis detected for
  Element           8    side           1
  Requires PN/PN-2 STRESS FORMULATION
---

Pn/Pn-2 runs, as expected. Granted that I have to use Pn/Pn-2 for mixed BC when not aligned with an axis, the problem is that the pressure is discontinuous, which is stated in the documentation for the Pn/Pn-2 formulation. This is evident when plotting the pressure in Visit. Is there a way to obtain a smooth (correct?) pressure field when using Pn/Pn-2? Or is there a way to use the Pn/Pn formulation with such boundary conditions?

Thank you,
Jean

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