[COMSOL_Users] EHD simulation by COMSOL

[hua.li94]

Hello, everyone. I just do the EHD simulation by COMSOL. But there are some problems about it. I just need a .mph file about EHD to learn it. Thanks very much. I really need your help.

[Sebastien Boisseau]

Hello

I wanted to know if you managed to get a .mph file of an EHD under Comsol.

Thanks

SB

Post by hua.li94
Hello, everyone. I just do the EHD simulation by COMSOL. But there are some
problems about it. I just need a .mph file about EHD to learn it. Thanks
very much. I really need your help.

[Ian Taylor]

I have a COMSOL EHD line contact model set up. Contact me for more details. It is really quite straightforward to set up. You need to write down the Reynolds equation in the weak form, using the general PDE part of COMSOL. Then you need to write down the equation for the deformed oil film thickness, using an integration coupling constant to do the complicated integral (and using the dest() operator). You also need an integration coupling constant to integrate over the pressure (you also need a penalty term to avoid negative pressures). The global equation to solve is that the integral over the pressure is equal to the load per unit length. Note it is also best if you non-dimensionalise all the parameters (the pressure, oil film thicknesses, distance etc) in the standard way.

I have found that the solution is actually more stable if you use Lagrange linear elements, although you need a reasonably fine mesh. If you use higher order elements, the pressure can get oscillations in it at high loads. Most of the solvers are capable of solving the problem, and if you optimize the model, you can get solutions in a few seconds.

Note that you DO NOT need to solve the elasticity equations numerically NOR do you need the structural mechanics module, you can do it all with the basic version of COMSOL.

Hope this helps
A link to the basic equations to solve is here:
http://www.comp.leeds.ac.uk/honglu/Hong_05.pdf
The relevant equations are (1), (2) and (3) in the above paper.

Post by Sebastien Boisseau
Hello
I wanted to know if you managed to get a .mph file of an EHD under Comsol.
Thanks
SB

Post by hua.li94
Hello, everyone. I just do the EHD simulation by COMSOL. But there are some
problems about it. I just need a .mph file about EHD to learn it. Thanks
very much. I really need your help.

[Sebastien Boisseau]

Hello.

Thank you for your answer.

But I think that we didn't mean the same thing with EHD : It meant Electro
hydrodynamic for me (i.e. : study of corona discharges).

Best regards
SB

[[e-mail] [COMSOL_Users]]

hi
i have this problam too.
pls if you find this file send for me
my id
***@yahoo.com
tanks

[[e-mail] [COMSOL_Users]]

Please how do I calculate local and average Nusselt number in a vertical enclosure
Onaolapo Olatayo

-----Original Message-----
From: "***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com>
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Date: 22 Jul 2014 11:51:48
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Subject: [COMSOL_Users] Re: EHD simulation by COMSOL

hi
i have this problam too.
pls if you find this file send for me
my id
***@yahoo.com
tanks

[Javad Rahimi [e-mail] [COMSOL_Users]]

hi

To calculate the Nusselt number for a vertical cylinder
If the cylinder diameter is large compared to its height
Churchill equation can be used



________________________________
From: ‪"***@yahoo.com [COMSOL_Users]"‬ ‪<***@yahoogroups.com>‬
To: ***@yahoogroups.com
Sent: Tuesday, 22 July 2014, 23:44:59
Subject: Re: [COMSOL_Users] Re: EHD simulation by COMSOL



 
Please how do I calculate local and average Nusselt number in a vertical enclosure
Onaolapo Olatayo
________________________________

From: "***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com>
Sender: ***@yahoogroups.com
Date: 22 Jul 2014 11:51:48 -0700
To: <***@yahoogroups.com>
ReplyTo: ***@yahoogroups.com
Subject: [COMSOL_Users] Re: EHD simulation by COMSOL
 
hi
i have this problam too.
pls if  you find this file send for me
my id
***@yahoo.com
tanks

[[e-mail] [COMSOL_Users]]

10cm by 5cm vertical cylinderical enclosure. Pls I don't know how to input the nusselt equtn in comsol. I hav two days to my final defence
Onaolapo Olatayo

-----Original Message-----
From: "Javad Rahimi ***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com>
Sender: ***@yahoogroups.com
Date: Tue, 22 Jul 2014 20:56:36
To: ***@yahoogroups.com<***@yahoogroups.com>
Reply-To: ***@yahoogroups.com
Subject: Re: [COMSOL_Users] Re: EHD simulation by COMSOL

hi

To calculate the Nusselt number for a vertical cylinder
If the cylinder diameter is large compared to its height
Churchill equation can be used



________________________________
From: ‪"***@yahoo.com [COMSOL_Users]"‬ ‪<***@yahoogroups.com>‬
To: ***@yahoogroups.com
Sent: Tuesday, 22 July 2014, 23:44:59
Subject: Re: [COMSOL_Users] Re: EHD simulation by COMSOL



 
Please how do I calculate local and average Nusselt number in a vertical enclosure
Onaolapo Olatayo
________________________________

From: "***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com>
Sender: ***@yahoogroups.com
Date: 22 Jul 2014 11:51:48 -0700
To: <***@yahoogroups.com>
ReplyTo: ***@yahoogroups.com
Subject: [COMSOL_Users] Re: EHD simulation by COMSOL
 
hi
i have this problam too.
pls if  you find this file send for me
my id
***@yahoo.com
tanks

[Javad Rahimi [e-mail] [COMSOL_Users]]

i am sorry

Because I do not know too much comsol
Please search YouTube.com
or comsol.com



________________________________
From: ‪"***@yahoo.com [COMSOL_Users]"‬ ‪<***@yahoogroups.com>‬
To: ***@yahoogroups.com
Sent: Wednesday, 23 July 2014, 0:33:22
Subject: Re: [COMSOL_Users] Re: EHD simulation by COMSOL



 
10cm by 5cm vertical cylinderical enclosure. Pls I don't know how to input the nusselt equtn in comsol. I hav two days to my final defence
Onaolapo Olatayo
________________________________

From: "Javad Rahimi ***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com>
Sender: ***@yahoogroups.com
Date: Tue, 22 Jul 2014 20:56:36 +0100
To: ***@yahoogroups.com<***@yahoogroups.com>
ReplyTo: ***@yahoogroups.com
Subject: Re: [COMSOL_Users] Re: EHD simulation by COMSOL
 
hi

To calculate the Nusselt number for a vertical cylinder
If the cylinder diameter is large compared to its height
Churchill equation can be used



________________________________
From: ‪"***@yahoo.com [COMSOL_Users]"‬ ‪<***@yahoogroups.com>‬
To: ***@yahoogroups.com
Sent: Tuesday, 22 July 2014, 23:44:59
Subject: Re: [COMSOL_Users] Re: EHD simulation by COMSOL



 
Please how do I calculate local and average Nusselt number in a vertical enclosure
Onaolapo Olatayo
________________________________

From: "***@yahoo.com [COMSOL_Users]" <***@yahoogroups.com>
Sender: ***@yahoogroups.com
Date: 22 Jul 2014 11:51:48 -0700
To: <***@yahoogroups.com>
ReplyTo: ***@yahoogroups.com
Subject: [COMSOL_Users] Re: EHD simulation by COMSOL
 
hi
i have this problam too.
pls if  you find this file send for me
my id
***@yahoo.com
tanks

[[e-mail] [COMSOL_Users]]

how and where do i type the churchhill equation in comsol?