Hello Everyone,
I am trying to perform CFD simulation of a 2D Evaporation problem.
It involves a stationary droplet resting on the surface of a heated wall of a duct, ( the shape of the droplet depends upon many parameters and I am assuming a random shape to simply the problem statement).
The wall has a constant heat flux and there is inlet flow of hot gas with fixed temperature
My objective is to evaluate how much time does it take to fully evaporate the water droplet and how does wall conductivity affects this.
I have been trying to model this problem in Fluent and I used Multiphase Mixture model but I am not able to setup the problem correctly and results does not make any sense to me.
Also, VOF model does not have evaporation-condensation model since its Isothermal model and does not take energy/ mass transfer into account ( this is what I understood from going through the Theory guide of Fluent).
Any suggestion from anyone who has performed similar kind of simulation before is highly appreciated.
Looking forward to listen from your guys.
May be able to help but need some clarification:(a) is the heat flux to the drop lspecified or is it based on the thermal environment of the flow in the duct wich determines the wall temperature of surface that the drop sits on. (b) what is the thermal environment of ambient gas phase to which the drop evaporates into (c) do you assume that the contact line of the drop is fixed or do you specified a fixed contact angle.
Hi Professor Brian,
Thanks for your reply.
a) The heat flux is based on the thermal environment of the flow in the duct and my objective is also to study the change in wall temperature due to drop evaporation. But, I believe it will be complicated to model.
Also the wet surface compared to the overall length of duct is negligible and I may assume the wall to be at constant temperature except for very small region influenced by droplet. Therefore, even if I assume a constant heat flux , I guess its a valid assumption.
b) The gas is air and it has a constant temperature around 400 degrees. The velocity profile is fully developed turbulent profile. c) A fixed contact angle ( Although, I didn't totally understand what is you are asking me. )
Dear Shashank Mishra,
I think maybe you can try DPM in Fluent to simplify the problem, and this may help you to grasp the main feature of your problem, i.e, droplet evaporation due to the heat and mass transfer with the environment surrounding the droplet. I have used the DPM in Fluent for the similar problem. I attached the article for your reference.
Good luck.
Dear Professor Bin Zhao
Thanks for your answer.
I have broken my project into two phases.
One is to see how much spray is evaporated while in flight domain and other is to see physics of heat transfer once it hits the wall.
The droplet surface deformation and its interaction while it hits the wall is not considered by me at present because I believe that will require dynamic meshing to visualize the shape of contact surface.
Also, in DPM, the wall boundary conditions are escaped and trapped if I am not wrong. With trapped boundary condition, the droplet hitting the surface evaporates immediately.
Do you think it is possible to include the effect of wall thermodynamics in DPM modelling as well.
Can you share your case files with me.
Thanks again for your time
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