Transient Solver for Multiphase Boiling Heat Transfer Case

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  • Last Post 30 January 2019
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farizanluthfi posted this 29 January 2019

Dear Respected User,

I have a query for determining the time step, number of time steps, and max. iterations for my case. Nowadays, I am working with a simulation of boiling heat transfer multiphase flow using RPI Wall Boiling Models.

I have done my single-phase flow with steady-state to achieve a fully-developed flow at the beginning of my simulation, and after that, I put my output value into my input for doing the multiphase flow case.

Any supports are appreciated! Thank you,

Best Regards,

Luthfi

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abenhadj posted this 29 January 2019

Boiling applications with RPI are generally ran with steady-state solver. Just start with the fully developed profile.

Best regards,

Amine

farizanluthfi posted this 29 January 2019

Boiling applications with RPI are generally ran with steady-state solver. Just start with the fully developed profile.

 

Could you please give the justification on what's the reason for taking RPI to be simulating with steady-state solver? Thanks.

 

Best Regards,

Luthfi

abenhadj posted this 29 January 2019

Because they are expensive to be run with transient solver. You can however use transient solver to run them. 

Best regards,

Amine

farizanluthfi posted this 29 January 2019

Because they are expensive to be run with transient solver. You can however use transient solver to run them. 

I have tried with using steady-state solver and it turns into diverged. My case is determining the subcooled boiling inside the helical tube. So, the goal is to investigate the subcooled boiling heat transfer inside the domain.

Do you have any suggestion for tackling this case? Any suggestion is appreciated. Thanks.

Best Regards,

Luthfi

abenhadj posted this 29 January 2019

Is it convective boiling? You need to have a coarse mesh towards the wall (yplus larger then 30-40) to use RPI efficiently. 

PS: do not quote my message as it is not really helpful for me. 

Best regards,

Amine

farizanluthfi posted this 30 January 2019

Yes, it is the convective boiling because in the domain I put on the velocities of the fluid so based on my basic knowledge it is definitely convective boiling. please do some correction if I had some misunderstood about this.

I have used fine mesh towards the wall (yplus around 11.235), so according to your suggestion, do I need to rectify the mesh into coarse one?

If possible, I could give you my case file so you could completely understand the problem. 

Thank you for your kindly support,

Best Regards,

Luthfi

P.S: thank you for your correction, I do apologize for all the caused. 

abenhadj posted this 30 January 2019

You require coarse mesh towards the wall. RPI is onlyvworkingvfor convective boiling. You will need a lot of patience to get things running. Good luck!

Best regards,

Amine

farizanluthfi posted this 30 January 2019

Dear Amine, Convective boiling is same with the forced-convection boiling, right? Okay, I'll try my best for my simulation. Thank you. Best Regards, Luthfi

abenhadj posted this 30 January 2019

Yes.

Please mark this topic as resolved.

Best regards,

Amine

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