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 mike August 27, 2004 14:12

high temperature object in water

hi,

i'd like to simulate high temperature (high enough to vaporize water) object enters water. could someone tell me some references? what issues i have to look at? numerical difficulties? etc. ?

thanks a lot, mike

 george August 30, 2004 03:29

Re: high temperature object in water

- coupling of heat conduction in body with heat transfer at surface - heat transfer at surface: evaporation of water: what kind of boiling ? do you want to model it (e.g heat transfer relation) or to simulate it (cfd for unsteady two phase flow with phase transition) ? - try "quenching" to get further references on physics

 mike August 30, 2004 12:33

Re: high temperature object in water

george, thanks for your reply. my problem involves large excess temperature so it's in the stable film boiling regime. i'd like to simulate the multiphase flow using cfd. i don't know where to start since there's so many things involved. i guess i should look into where/how to simplify the process first before taking on the whole thing. any suggestion? mike

 a. August 31, 2004 05:45

Re: high temperature object in water !!!

Hi,

I was thinking about solving the flow in a pipe, which walls are suddenly extremely heated. SO I could expect boiling. Unfortunately, I cannot find any good book about boiling, or an example of such a solution. COuld you please HELP?

 george August 31, 2004 07:45

Re: high temperature object in water

- if you want to simulate the whole thing, you have to consider the 2phase flow with phase transition - there you have a continuous interface (between vapor and liquid) so some vof or level-set method could be used. extra care about what is happening at the interface : the physics of the phase transition liq-> vap and vap->liq should be considered - check the physics what the interface is doing: for very high subcooling and very high flow velocities you can assume smooth interface, if not you have instabilities (waves and ripples) you have to consider. is the problem transient ? are there any parts of the problem that can be assumed steady state ? - for how to simplify your problem maybe check the more traditional, analytical engineering type approaches to your problem or look in related areas. some hints: metallurgy: quenching , film cooling. nuclear: LOCA (loss of coolant accident), cooling of hot fuel rods. heat transfer (equipment): convective boiling in and around tubes - there was some cfd done for film boiling: V.K. DHIR (in ASME J.Heat.Trans (some 5-3 years ago), TRYGGVASON (did some computations with his level set method I recall) (although the info might be somewaht outdated now) (it was about the deformation instability of the interface)

good luck in dealing with a very nontrivial problem

george

 mike September 1, 2004 12:11

Re: high temperature object in water !!!

you could look into: 1) Adrian Bejan, convection heat transfer 2) Van Carey, liquid-vapor phase-change phenomena good luck.

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