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You are here: Fluid Machinery Templates and Tutorials > Ball Valve > Ball Valve Tutorial > Defining Physics and Conditions

Defining Physics and Conditions

The physics and conditions are specified as follows.

Adding Modules
  1. Ball Valve is automatically added to the Model Panel, when the Ball valve template is used to generate the mesh.
  2. Click Select Modules in the Model Panel. The Physical Model Selection dialog box opens.
  3. Select Turbulence, Cavitation and Translation (1 DOF) under Available Modules and click Add.

  4. Click Close to close the Physical Model Selection dialog box.

  

Figure 6.614 - Adding modules
Ball Valve Operating Parameters
  1. Select Ball Valve in the Model Panel.
  2. Select Translation (1 DOF) from the Dynamics drop-down list in the Model Tab of Properties Panel, to link the motion of the Ball Valve to the Translation (1 DOF) module.
  3. Set Minimum Gap Size as 5e-05 m and Maximum Displacement as 0.002 m.
  4. Select Automatic in the Closure Model drop-down list.

 

  

Figure 6.615 - Ball valve-Operating parameters
 

Note:Closure Model determines whether the flow is fully blocked at the Minimum Gap Size.
Translation (1 DOF) Operating Parameters
  1. Select Translation (1 DOF) in the Model Panel.

  2. Enter the Time Definition parameters in the Model Tab of Properties Panel.

    • Number of Cycles: 4

    • Number of Time Steps per Cycle: 100

    • Motion Frequency (Hz): 100 1/s

  3. Select Force Balance in the Motion Type drop-down list.

  4. Enter the parameters for Motion Type as follows.

    • Body Mass: 0.0042 kg

    • Spring Constant: 5000 N/m

    • Spring Preload Force: 5 N
  5. Enter Movement Direction as 0,-1,0.
´ Note:  The Number of Time Steps per Cycle is an important parameter and needs to be large enough to achieve a smooth solution.
 

Figure 6.616 - Translation (1 DOF) - Operating parameters

 

 

 
Boundary Conditions

The boundary conditions for the Valve are preset by the Valve Template Mesher and are specified as follows:

  1. Select the entities under Boundaries in the Geometric Entities Panel, as shown in Table 6.34.
  2. In the Model Tab of Properties Panel, verify the boundary type in the Ball Valve drop-down list, as shown in Table 6.34.
Boundaries Ball Valve Boundary Type
ball Valve
ballvalve_cylinder Cylinder
ballvalve_end Valve End

Table 6.34 - Valve Boundary type

Inlet
  1. Select ballvalve_inlet from the Boundaries list in the Geometric Entities Panel.
  2. Select Inlet from Ball Valve drop-down list in the Model Tab of Properties Panel.
  3. Click Edit Expression icon in Inlet Pressure to open the Expression Editor dialog box .
  4. Copy and paste the expressions written under Description drop-down list for Global Expressions, see Figure 6.617
    5. ClosedDescription

    fre = 100 # Hz

    P0 = 3E5 # Pa

    dp = 2E5 # Pa

    inlet_p = P0 + dp*sin(2*pi*fre*time) # Pa

  5. Click OK and enter inlet_p for the Inlet Pressure in the Model Tab of Properties Panel.

 

  

Figure 6.617 - Inlet conditions
Outlet
  1. Select ballvalve_outlet from the Boundaries list in the Geometric Entities Panel.
  2. Select Outlet from the Ball Valve drop-down list in the Model Tab of Properties Panel.
  3. Enter Outlet Pressure as 101325 Pa.

 

 

 

 

  

Figure 6.618 - Outlet conditions
Fluid Properties
  1. Select Volumes in the Geometric Entities Panel.
  2. Select Model Tab in the Properties Panel.
  3. Enter the parameters in Property list as follows.
  • Material: Oil
  • Dynamic Viscosity: 0.007 Pa-s
  • Density: 800 kg/m3

  • Liquid Bulk Modulus (B0): 1.5e+09 Pa

  • Liquid Reference Pressure: 101325 Pa

  • Saturation Pressure: 400 Pa

  • Enter the parameters for Operating Conditions as follows.

    • Gas Mass Fraction: 9e-05
    • Operating Temperature: 300 K
    • Starting Pressure: 101325 Pa
    		•   

    Figure 6.619 - Fluid properties

     

     

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