Icepak 教程ＰＰＴicepak-07-solver

1、Solver,Topics,Problem setup basic parameters Solution settings Solver Monitoring solution progress Parametric studies Transient solutions,Problem setup,Model Tree Problem setup,Problem setup panel,Parametric trials panel,Title and notes panel,Define time variation: steady state transient,Define equa

2、tions to solve: Variables solved Flow situation Heat transfer mode,Define default values: Ambient values Default materials Initial value,Problem setup: Basic parameters,Middle portion of problem setup panel Check Flow to solve Navier-Stokes equation Check Temperature to solve energy equation Check G

3、ravity vector to include buoyancy terms in the Navier-Stokes equation (free convection) Radiation on include radiation heat transfer in energy solution Appropriate flow regime Laminar or Turbulent (zero equation/ 2 equation/ RNG models),Problem setup: Equations to solve,Problem setup: Equations to s

4、olve,Useful Notes Conduction only problems Check only Temperature and uncheck Flow Ensure appropriate heat transfer from walls Forced convection problems flow is usually independent of energy equation possible to solve for flow alone first and then for energy alone Natural convection problems flow a

5、nd energy equations are interdependent and must be solved together Radiation heat transfer is significant and should be included Turbulent flow Zero equation is sufficient for most cases in electronic cooling 2 equation and RNG models may be used for detailed wake behavior, jet impingement, etc,Solu

6、tion settings Solver setup,Purpose Solver termination criteria Max. no. of iterations Convergence criteria for Flow equations Energy equation,Select Accept to accept changes Reset changes all fields to default values - also displays the Reynolds/ Grashoff* number for the problem in the messages wind

7、ow,*These numbers are based on maximum cabinet dimension, characteristic velocity and temperature, and only serve as a very approximate guideline. The user should judge whether the flow will be laminar or turbulent.,Advanced solver controls Discretization scheme Under-relaxation factors Multi-grid l

8、inear solver Precision level single/ double,Solution Settings Advanced solver setup,Under-relaxation a note This determines the relative amount of change in the variables after each iteration for simple forced convection situations use 0.3 for pressure and 0.7 for momentum for natural convection, or

9、 complex forced convection situations (examples twisted flow passages, sudden changes in cross section, densely packed models) use 0.7 for pressure and 0.3 for momentum,Solving the momentum eqs for velocity (V) using current pressure (p) filed,Solve the V-p coupling eq. for pressure using the new V

10、field,Solve the T, k, e eqs using the new v, p field,Converged?,Stop,Yes,No,Solver - The SIMPLE Scheme,Solver Starting the Fluent solver,The basics: Solution ID - type in a unique ID default is + Write overview of results summary report of mass and energy balance, fan operating points, etc. Start so

11、lution starts the Fluent solver residuals window opens shows residual curves for each equation: continuity, momentum in x, y, z directions and energy solution will stop when the residual curves satsify convergence criteria, or number of iterations (both specified in Solver Setup panel),Solver Residu

12、als and Overview report,Stop solver,Change scale,Plot options,Residual window,Overview report,Solver Advanced features,Restart from an existing solution Specify the existing solution ID Select Full data if the current mesh is the same as in the restart solution Select Interpolated data if mesh is di

13、fferent Job can be submitted to any computer on the network and at any time Available in forced convection problems - first solves flow equations alone till convegence, then solves energy equation - useful in large models Can disable radiation here Auto-save interval =N solution is saved after every

14、 N iterations,Monitoring solution progress,Monitor object center: Drag selected objects into the Monitor points branch Then double click the object to open the variables panel Select variables to monitor and accept,Monitor any defined point: Go to Main menuSolve Solution monitor Define points and va

15、riable to monitor at that point,Why monitor: One more way to ensure convergence Possible to monitor velocity, temperature or pressure at specified points 2 ways to define point monitors: monitor object center, or any defined point,Parametric studies Defining variables,Uses: optimization tool allows

16、definition of variables and generates solutions for each value of the variable How to define a variable instead of numerical value, enter a string as the variable name Variable name must always begin with $ In the example shown here the heatsink overall height “$HS_ht” and the fan flow rate “$cfm” a

17、re the variables After the variable is defined Icepak prompts the user for the initial numerical value of the variable Additional values can be assigned to the variables under Model tree Problem setup Parameters Parametric variables can be used in equations for example: for the heat sink specify Ove

18、rall height as “$extra_ht + 4” mm The characters -, , # should not be used in parameter names,Parametric studies setting values & solving,Specify values for the variables in the “Parameters” panel Then click on “update trials” This updates all combinations of the variables in the “Select trials” pan

19、el and opens the “Trial naming” prompt Numbered: solution ID is serially numbered with a prefix Values: solution ID is named based on the value of the parametric variables Solving: in the solve panel select “perform multiple trials”,Parametric studies select/ set/ restart ID,All checked trials will be solved uncheck to exclude,Set button applies the combination of p