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Water VOF became fixed per time, although water velocities are increasing

    • Walaa Elhamamy
      Subscriber
      Hello, 
       
      I need help to understand the physical meaning of this graph, where there is a mistake that I can't get. I am simulating a flood, my inlet boundary condition is a velocity inlet (transient table). I am simulating 15 minutes of flood. 
       
      The velocity is increasing in the boundary condition, so logically, the VOF should be growing as well. Eventually, the water should fill the whole space.
       
      However, when the VOF reached 0.6, at a time of almost 5 minutes (300 sec), it stopped growing and kept almost constant, although, the velocity in the boundary condition table kept growing. 
       
      Could anyone help to understand where is the problem? 
       
       
       
    • Rob
      Forum Moderator

      Please post some images of the flow field. How did you define the report?

    • Walaa Elhamamy
      Subscriber

       

       

       

       

    • Walaa Elhamamy
      Subscriber

      Are these screenshots clear? do you need other information? 

    • Rob
      Forum Moderator

      How does the air escape? 

    • Walaa Elhamamy
      Subscriber
      I am defining the whole ceiling as a pressure outlet, is this enough? I am not defining any vents. 
       
      Additional note: 
      I made another try to examine if there was a problem in the transient table, I redefined the velocity inlet to a fixed value, however, the same exact behavior happened, at almost VOF=0.6, and kept almost stable. 
    • Walaa Elhamamy
      Subscriber

    • Rob
      Forum Moderator

      That should be fine. How is the inlet defined? 

    • Walaa Elhamamy
      Subscriber

      I divided the inlet into two parts (velocity inlet and pressure inlet). I don't want the water to enter from the whole door height (occupied the whole height I mean).

      The total door height is 1.7 m, and a part of 0.35 m, near the ground, is the water inlet and I defined it as a velocity inlet, the rest of 1.35 m above I defined as a pressure inlet. 

       

       

    • Rob
      Forum Moderator

      What mass flow of water is coming out of the pressure inlet? 

    • Walaa Elhamamy
      Subscriber

      sorry, I don't understand what you mean. 

      but I am attaching screenshots of related settings to the pressure outlet. 

       

       

    • Rob
      Forum Moderator

      Please check the mass flux report on the pressure inlet - specifically for the water phase. 

    • Walaa Elhamamy
      Subscriber

      I am sorry, would you help me with how to check this? I can't find it. 

    • Walaa Elhamamy
      Subscriber

      Is this what you mean? 

    • Rob
      Forum Moderator

      Results (tab) > Reports > Fluxes 

      I suspect the water is entering the domain through the inlet, and then overflowing back out of the pressure inlet. 

    • Walaa Elhamamy
      Subscriber

      oh, does the attached screenshot support what you said? I attached the report of mass flux as you asked. 

    • Rob
      Forum Moderator

      Yes, you have 384.67kg/s water leaving through the inlet. I suspect that ties up with the inflow. 

    • Walaa Elhamamy
      Subscriber

      I see, thanks for your help. do you have any idea how I can fix this ?

    • Rob
      Forum Moderator

      Maybe turn it into a wall? 

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