Step 6: Specify Boundary Conditions and Initial Condition
The boundary conditions for the problem are shown in Figure1. The WARTSURFACE has a convective boundary condition and all other boundaries have zero heat flux condition (insulated boundaries).
Specify BC on the Boundary WARTSURFACE
1) In the Boundary Conditions window, select WARTSURFACE in the Entity field.
2) Select Constant from the drop-down menu next to the Heat Trans Coeff text-box
3) In the Heat Trans Coeff text field, Type 5000
4) Select Constant from the drop-down menu next to the Ref Temperature text-box
5) In the Ref Temperature text field, Type -196
6) Click on Apply
Specify BC on the Boundary WARTSIDE
1) In the Boundary Conditions window, select WARTSIDE in the Entity field.
2) Click on the Temperature button and select Heat Flux from the drop-down list
3) Select Constant from the drop-down menu next to the Heat Flux text-box
4) In the Heat Flux text field, Type 0
5) Click on Apply. Similarly, specify boundary conditions for the SKINSURFACE, SKINSIDE and SKINDEEP boundaries (for all heat flux = 0) and then proceed to the next step.
6) Click on Initial Conditions. We will now supply the initial conditions to the solver.
Specify Initial Condition
The temperature inside the skin and the wart is 370C initially.
1) In the Initial Conditions window, select SKIN from the Continuum List field
2) Select Constant from the drop-down menu next to the Temperature text-box
3) In the Temperature text field, Type 37
4) Click on Apply. Similarly, specify an initial condition of 370C for the WART and then proceed to the next step.
5) Click on Solver Controls. We now specify the method to be used to solve the nonlinear system of equations and the time integration method for a transient analysis.
Step 7: Specify Solver Controls
We use the method of Successive Substitution (S.S.) with 50 as the maximum number of iterations per time step to solve the set of equations for this problem. This is the default solver setup and so we do not change it
We now specify the time integration method for the time dependant problem. We use the Backward Euler time integration scheme with a variable time increment for this problem. These are the default values and so we do not change these.
Specify the Time Integration Method for the transient problem
1) In the Solver Controls window, click on Unsteady Solver
2) In the Variable Time Stepping block, Set Start Time (TSTART) to 0. We specify the starting time to be 0.
3) Set End Time (TEND) to 15. The ending time for the transient problem is set to 15 s.
See rest of steps below:
4) Set Time Step (DT) to 0.001. DT is the time increment used at every time step; for variable step integration DT is the time increment for the initial few time steps which we will specify in (6) below. DT is set as 0.001 s for the problem here.
http://www.cadfamily.com/html/Article/Cryosurgery%20in%20FIDAP-Part%20B_611_1.htm
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