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How to define a lineary or exponetially closing valve profile in water-hammer problem and pipe flow modules for a straight piping system
Posted 1 juil. 2016, 04:47 UTC−4 Fluid & Heat, Acoustics & Vibrations, Computational Fluid Dynamics (CFD), Materials, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers Version 4.4 0 Replies
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I want to model water-hammer phenomena for a linearly closing and exponentially closing valve condition in an straight piping system. The piping is connected with constant reservoir at one end and other end is connected with fast closing valve.
Comsol provides example problem with sudden closure of valve with the above layout.
I tried to provide some boundary condition like u0*t[1/s]-1, +1, -2.1 and +2.1 but I am not getting the desired flow velocity at valve location. It seems that velocity is coming to zero and then negative in 0.0001 sec. The solver is being used is transient solver with (0, 1e-03,0.1) and I changed these values but nothing changes.
I see some options like interpolation, step function and analytical function but I do not know how to use them properly. I tried with step function as step1 with From (1.5) To (0) and Location 1 but the desired velocity pattern could not be developed. What is the meaning of Location here whether it is distance or something else.
Whether I can use interpolation function for defining variable Boundary condition as linear closing of valve. I get int1 and the plots are correct but 'HOT TO IMPLEMENT IT'. I have a n initial velocity u0 =1.5 m/s and if I selected Velocity as boundary condition then whether I should write u0*int1 or something else as this is not working.
Please help to understand these things.
Hello Pavan Patel
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