This shows that the air (initially under 10 bar of pressure) would take 74 secs to evacuate through a 50 mm dia opening. Both can be on the same sheet .įor the tank evacuation I entered 25 time steps for the calculations. To prove it works, I have created a Calculator sheet for calculating the Reynolds Number of water flowing at 10m/s over a cylinder of 100 mm diameter and also the results of the tank evacuation. I would rather Flow create this for me than attempt to build it in Excel! Below is the formula for a tank evacuation through a single opening. You can tick the preview box and then see the formula being created. Below I have shown the ones for the dimensionless parameters. This opens up the library and you can browse to a host of common equations. It will initially be empty but you can start adding formulae by clicking on the fx icon at the top of the sheet. This opens up a table much like a Excel spread sheet. You can access this tool from the Flow drop down menu under Tools > Calculator. The beauty is that for a range of common calculations the formula is available to be added from a library saving you the trouble of building it from scratch with the possibility (or likelihood in my case) that you get it wrong! Examples of calculations are dimensionless gas constants (like Reynolds, Knudsen, Stanton, Nusselt, Prandtl etc.) flow rates pressure coefficients and even the time to evacuate a tank of pressurised fluid. You can even create your own bespoke formulae and save them for future use if you wish. It allows you to calculate a range of fluid parameters where there is a known mathematical equation to calculate the fluid dynamic or thermodynamic value. However, very few users are aware that there is a useful 'Gas Dynamic Calculator' hidden away within Flow. SOLIDWORKS Flow Simulation is a superb tool for analysing fluids and helping you design products that require you to understand fluid flows, pressures and temperatures.