Learning Forum

[sinan ozbolgili]

Hi, 

Its been ,ong time I am tring to solve pool boiling around horizontol tube in a water tank. 

I need to solve till 1 second but when heat fluex reach 60000W contunity starty to not convertaging .

What can be reason ? 

[Rob]

What is the flow field doing? 

[sinan ozbolgili]

Turbulant flow,

 

pelase see  below pic. 

 

[Rob]

OK, and the flowfield? 

[sinan ozbolgili]

Hi, not understand by asking flow field. what should be flow filed ?

[sinan ozbolgili]

is below one ?

[Rob]

 

Where is the heat going? What is the fluid velocity? How much gas has been created? If you do some post processing on a converged solution what do you see?

 

[sinan ozbolgili]

no need to give flueid velocity it eubler pool boiling,  heat will be transffer from circle tub to water.  

Whater will be boiled and bubble will go  to [ressure outler 

[Rob]

And pictures showing this? 

[sinan ozbolgili]

yes, actually I already did for  tube wall tempreture 379.15 K but when I try for 380.65 I  see after waiitng sometimes is starts to not convertage 

[Rob]

And without knowing what the flow is doing when it's not converging I can't make any suggestions as to how to fix your problem. 

[sinan ozbolgili]

It is tubulant flow

[Rob]

Pictures? 

[sinan ozbolgili]

here all pics 

 

 

 

 

 

 

 

 

 

 

 

 

[Rob]

OK, and what is the flow doing? Contour and vector plots might be useful. 

[sinan ozbolgili]

here

[Rob]

OK, so the gas plume rises. That's a good start. How does the velocity look? 

[sinan ozbolgili]

Velocity also seems okey but as I spefciifef when heat fluxk reach 60 KW it will start to not convertage . 

[sinan ozbolgili]

do you have any suggestion ? 

[sinan ozbolgili]

Vector of vapur velocity at 0.1  second

[sinan ozbolgili]

Hi Rob, Those pic I shared above were for Twal=379.15 K and FLuent is siolving this problem as can be seen from voluma fraction 

 

When I increase Twall to 380.65 K and bubble coefficient from 0.2 to 0.6 FLuent not solving after 0.25 second. 

 

 

[Rob]

OK, so what is happening to the flow at that point?  Also bear in mind I can't download images so if they're not clear I'm guess what's going on. 

[sinan ozbolgili]

Bubble will raise to outlet pressude but it will not cionertage to 10 ^(-4) . It will stay always around 10^(-2) . There will be fluctuation. 

Do you think this is hapening becasue of turbulent kinetic energy in inizalation ? Should i make it too low? 

[Rob]

I suspect it's more likely some effect of the boiling.

[sinan ozbolgili]

Does it mean ''normal'' ? no need take any action ? 

[Rob]

Please elaborate. 

[sinan ozbolgili]

Hi Rob,

 

may I ask for that kinf od analyse which  interfacial area need to be selected ?

-ia particle
- ia symmetric
- ia ishii 

 

[Rob]

Check the Theory Guide, it should explain what's most suitable for when. 

[sinan ozbolgili]

could not find, there is interfacial area concentration but there is no interfacial area only thats why I am aksing  

 

[sinan ozbolgili]

could you pelase support  ? 

[Rob]

Odd https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v232/en/flu_ug/flu_ug_sec_mphase_using_steps_eulerian.html%23flu_ug_sec_use_bm