Regarding choosing correct boundary condition

2024 6 21
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更新时间：2024 6 21
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Hi,
I have a condition where at the left boundary and the right boundary I need the flux to be non-zero.
Thus, the equations
pL + qL*fL = 0 and pr + qr*fr = 0 are such that fL and fr being non zero is making my equation hard to determine the values for pl, ql as well as pr, qr.
Plz tell me how should I approach for the same.
with regards,
rc

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 采纳的回答

Torsten
Torsten 2024-6-21
编辑：Torsten 2024-6-21

0 个投票

If you set qL = 1 and qr = 1 and you defined f as f = D*du/dx in the function where you need to specify [c,f,s], you can specify the flux in pL and pr.

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Rahul
Rahul 2024-6-21
编辑：Rahul 2024-6-21
Hi Torsten,
Thanks a lot.
But I think the term Pi_s in the flux is a problem. How to fix this term?
rc
Torsten
Torsten 2024-6-21
I cannot open your bc.pdf. Thus I don't know what Pi_s is.
Rahul
Rahul 2024-6-21
Hi Torsten,
plz find attached.
rc
Torsten
Torsten 2024-6-21
What is under the d/dr ? What did you specify as f ? What do you want to set as boundary condition ?
Rahul
Rahul 2024-6-21
Hi,
the flux is
f = -1*u(2)*((v0+v1*epsilon_v)*DuDx(4)+ pi_s);
Here,
v_phi denotes the velocity denoted here as u(4).
Also,
pi_s = k * epsilon_v (1-sigma * dp/dr)*gamma
where, k denotes coefficient of equation.
rgds
Torsten
Torsten 2024-6-21
编辑：Torsten 2024-6-21
What is u(2) ? Is it n ?
The flux for u(4) should not include pi_s.
Put 1/r d/dr(r*n*pi_s) in the source term s(4) and remove it in the specification of f(4).
Rahul
Rahul 2024-6-21
Hi, Torsten,
Yes, u(2) is n.
Ok, I'll do so. Thanks a lot.
rgds,
rc

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