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TransAT Tutorial Manual                                                        4.2. Sloshing



                   • Select Level-set in the equation tree then set the following
                     Convection Scheme : QUICK




               4.2.5.5   Initial Conditions
                  In TransAT, the user has the possibility to create custom initial conditions. For two–phase flow
               simulations especially, the initial gas–liquid interface topology has to be specified by the user.
               This is achieved in TransAT using an XML file initialconditions.xml.


                  For this specific case, the only variables that are being initialized are simply the ones that we
               are solving for, i.e. velocity and pressure, and the Level-Set function which defines the topology
               of the gas–liquid interface.



                  For this case, the aim as far as initial conditions are concerned, is to define where in the domain,
               each phase should be. To gain the best perspective on the sloshing effect, the simulation starts
               simply with phase 2 (water) in the lower half of the domain and phase 1 (air) in the upper half.
               The initiated Vibrating Body Force will then cause the entire body of both fluids to vibrate
               with a frequency of 0.4 Hz and a change in velocity of both fluids should be witnessed almost
               immediately.


                  To be able to use custom initial conditions in this case, the file initialconditions.xml has to be
               placed in the project folder. For this case, a ready-made initial conditions file available in the
               TransAT Tutorials folder will be used to initialise variables over the domain. More information
               can be found on the generation of custom initial conditions in the Custom Initial Conditions
               chapter of the TransAT User Manual .


                   • Click Files in the top left corner then select Save to save the settings of the simulation

                   • Copy the file initialconditions.xml from the folder
                     Public/Documents/TransAT5.7/Tutorials/4.2 - sloshing to your project folder.

               The simulation must now be re-loaded to take into account the initial conditions settings set in
               initialconditions.xml.

                   • Click Files in the top left corner then select Open Project


                   • Select the project file of the simulation e.g. sloshing.stt.






                c 
Ascomp AG Switzerland                    141                                  Version 5.7
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