ANSYS

UDF has to be compiled, can’t be interpolated Steps launch Fluent from the Command Line For ansys 16.x, launch Fluent from the Command Line using the VS2015 x86 x64 Cross Tools Command Prompt (not x64 x86 cross tools) 1)      Open the Start screen (press Windows button on your keyboard, Type ' VS2013 x86 x64 Cross Tools Command Prompt ' 2)      Navigate to your working folder, i.e. the folder where your case and data files are (.cas & .dat). 3)      Type “fluent” in the command window to launch Fluent   or   “ C:\Program Files\ANSYS Inc\v161\fluent\ntbin\win64\ fluent.exe ” (quotation signs included, in case of standard installation; fluent version: 16.1). 4)      Make sure that on the Environment tab 'Setup Compilation Environment for UDF' is ticked. The default address is fine. 1.       Read mesh/cas file 2.       Setup turbulence model/boundary conditions, etc. 3.       Compilation a.       Define/user-defined/functions/comp

** Turbulent viscosity limited to viscosity ratio of 1e+05 *** reason The possible *causes* for large turbulent viscosity ratio include: - Bad initial conditions for the turbulence quantities (k and e) - Improper turbulent boundary conditions - Skewed cells *** solution If the problem is not caused by *bad mesh*, then *the beginning of the phenomena* can usually be avoided by: -Turn off solving *turbulence equations* for the first 100-200 iterations -Turn on turbulence and continue iterations If the problem occurs *in the middle of the iteration process*, then use the following procedure: - Stop the iteration - Turn *off* all equations except the *turbulence equations* - Increase turbulence under relaxation factors (URFs) (k and e) to 1 and iterate for 20-50 iterations - *Turn back all equations* and reduce the turbulence URFs to 0.5-0.8 and then continue iterations - Repeat the above steps for several times For *faster convergence*, it might be useful to obtain an initial solution wit

‎ Table of Contents 1. Reverse flow    reversed_flow 1.1. reasons 1.2. solutions 1 Reverse flow    reversed_flow It is common to encounter the regions of reversed flow at the initial stages of the simulation – This is normal. However, if the “reversed flow” warnings do not disappear as the simulation progresses, then one needs to address the issue and move the outlet boundaries to a location where the inflow is no longer encountered. Normally, it has to do with the outlet boundary condition. if you were to use the "pressure outlet" boundary condition at the outlet, your outlet must be set far away from the object of interest. In Fluent, I normally use the " outflow" boundary condition at the outlet and it does not give me reverse flow. 1.1 reasons It is virtually impossible to prescribe correct values for varying turbulence characteristics, temperature and species concentrations in those cells

Calculate Cp history using Matlab input data : unscaled time history of moment/thrust example of input data, "moment.out" 4283 6.983 -0.1910873139538953 4284 6.984 -0.191019809738711 4285 6.985 -0.1909838904131738 4286 6.986 -0.190943968230172 4287 6.987 -0.1908886443401208 4288 6.988 -0.1908541205872921 1. To load input data: > load moment.out 2.  extract *time* and *unscaled moment* and assign it to a variable named "m" > m=moment(:, 3);    # assign the 3rd column data of "moment.out" to variable "m" > time = moment(:,2); 3. calculating power coefficient, Cp cp=coeff(m);  # "coeff " is a function to calculate the Cp of 3 rotor  based on input moment (one rotor ) 4. assign "time" and "cp" variables to a new variable "cp_his" > cp_his = [time cp]; 5. export/save the workspace variable, "cp_his", to a txt file > save -ascii cp_his.txt cp_his ## syntax: save

‎ Table of Contents 1. TUI 1.1. Examples 1.1.1. Steady 1.1.2. Unsteady 1.2. discretization schemes 1.3. Turbulence model 1.4. Reference 1.5. Save residual 1.6. Journal 1.6.1. record journal GUI 1.6.2. The interactive TUI inside Fluent helps: 1.7. define 1.7.1. boundary-conditions 1.8. change rotational velocity of moving reference frame 1.8.1. batch model 1.8.2. interactive console TUI 1.9. set background color 1.9.1. invalid command [background] 1.10. syntax 1.11. Batch model 1.12. Boundary condition 1.12.1. Inlet BC 1.13. Animation/residual/monitor on cluster 1.14. Solver 1.15. Change pressure-velocity-coupling model in batch mode 1.16. time step size 1.17. Modifying the View 1.18. initialization 1.19. discretization schemes 1.20. Set under relaxation 1.21. log of execute makefile 1 TUI keywords: Background Execution on Linux Systems, journal file Programming language : Scheme , as a Lisp dial