2 Replies Latest reply on May 4, 2015 8:27 PM by Izaz Ullah

    air flow and water evaporation

    Izaz Ullah

      Hi all,

       

      I have a problem set up as shown in the fig.1. The goal is to investigate small container surface dryness through air flow over it.The air flows over the bottom surface of the small container due to suction from the vacuum pump.  The bottom surface of the container has small amount of water (10ul). I want to investigate the dryness of this surface as the air flows over it. I have modelled the air flow as shown in the fig.2. but having trouble how to set up water condition on the surface and determine corresponding evaporation/dryness? Any suggestions to solve this? Thank you.

       

       

      Izaz

       

      fig 01                                                                                                          fig 02

        • Re: air flow and water evaporation
          Jared Conway

          there is no way to simulate the water at the bottom as a "free surface" of water

          similarly there is no way to estimate the evaporation (phase change)

           

          if your analysis is setup the way it should be, your best bet is to infer what may happen to the air based on temperature and pressure...etc.

          • Re: air flow and water evaporation
            Izaz Ullah

            Thank you Jared for your feedback.

             

            Since I am only interested in the interaction of the air with the bottom surface which would determine whether the evaporation would take place or not,depending on the humidity of the air and temperature of the bottom surface. The shear stress plot at the  bottom surface gives a good indication of the air-surface interaction,as shown below. However, i am trying to take the analysis to the next level by having some concrete evidence that the air is doing the job it is assumed to,i.e. drying the bottom surface.

             

            As you've just mentioned, we cannot simulate water and there is no phase change etc. What condition do you recommend for the bottom surface which would help in determining the water condition there,any idea please ?

             

            Can we do tracer study in such a case by having some concentration at the bottom and monitoring it over a steady state/ transient period ? If yes could you please guide me how?

             

            Thank you again Jared.Much appreciated.

             

            Izaz