Discussion Forum

Dear Mehrez,

Would you mind send a copy of the model to me since I have been working on high reynold number problem but can not get any convergent solution so far.

Thanks a lot,

Jian

Dear Mehrez,
may I ask you informaton on how to apply Navier Stokes with coefficient form? i´m stuck in a MHD problem, without the possibility to use , due to license, the CFD module.

Thanks in advance!
Gianmarco

Hi dear Gianmarco
I've implemented NS equations under General PDE module. Is it what you want ?

Dear Mehrez,
really thanks if it´s possible, cause i cannot understand how to start with, it will be a very big help!

Ok no problem.
Just send me the form of your equation.
Do you want your equation to be implemented on Comsol under PDE weak form or general form ?
Mehrez

Dear Mehrez ,
i attached the photo related to theory i´ve been follwing (it´s the TEMPUS european programme, 2012): concerning the weak form, i don´t know actually what could fit to my project: if i had the possibility ( but i i´m working with a workstation that has a few problems with the comsol forum itself, but strangely not the support one) i will send you the file. it´s easy to see it, it´snot so compicate: just i need to understand how to work with pde. i think weak form won´t be used for a simple case like this

Thanks for everything
Gianmarco

i forgot to say, the equations at the top of both photo are the equation i need to use, one with dimensional coefficient and the other in the adimensional form,'; from here i don ´t know actually what to take

still thanks

I have sent you the model in a private message.
Hope it will halp you.
Mehrez

Dear Mehrez,
I'll be thankful if you can help me out on a similar problem.
I am trying to model a non-isothermal fluid flow problem, in which mass is not conserved within the domain. There is a vapor flux that exits the domain as soon as it is formed.

The problem with the fluid flow module is that I am not able to override the mass conservation equation. I have an expression for the mass flow rate of vapor, but I do not have a way to incorporate it into the model. I have read that using weak expressions helps, but I do not know how to implement that either.

Hence I decided to use the coefficient form PDE, where I can define the equations as per will. I need to know how to implement the compressible Navier Stokes equation in the coefficient form, with all the diadic terms. Kindly help me out on this.

I also look forward to any suggestions/guidance on using the weak form for Navier Stokes' mass conservation equation.

Thanks and regards
Syed Nadeem Akhtar

Hello,

I am very interesting to write my own equations. Please Mehrez can you send me your NS model in PDE form? I would be a starting point for me to understand PDE implementation

jgivernaud@emix.fr

Best regards

Hello,

I am very interesting to write my own equations. Please Mehrez can you send me your NS model in PDE form? I would be a starting point for me to understand PDE implementation

912437789@qq.com

Best regards

Hi Mehrez,
Please, i believe this will really be a good starting point for this my problem. Can you send me your NS model in PDE form? and how do i write temperature Eqn. together with the Navier stokes Eqn.

Am trying to solve 2D coupled navier stokes equation with temperature equation in comsol version 4.4 but don't really know how to input the temperature equation along side with the navier stokes equation as shown below
∇⋅v = 0
( ∂v/ ∂t) +(v ⋅∇v) = −∇P + k∇^2v + F
( ∂T/ ∂t) +(v ⋅∇T) = B∇^2T

and how do i remove this term (∇⋅v)^T in the momentum equation as it is in comsol

Good Morning Mehrez,

I want to implement the simulation of a suspension through an Annulus using the coefficient form PDE, as the built in models do not have the required equations that I need.

So I want your help as to how to implement a simple Navier Stokes equation using coefficient form PDE where the velocity has three components and how to specify the inlet and outlet conditions.

Thank You

Dear Mehrez

Hi, Mehrez, recently I encountered a similar problem for apply the incompressible condition.. SO could you please send me a copy of the general form pde? It will help me a lot if you could give me a hand!

xdengae@connect.ust.hk
Thanks a lot!

Hey Mehraz!

I am facing the same problem with the coefficients when I use the Coefficient form PDE to write the Navier Stokes Equations. Can you help me out??