NX CAE Tips & Tricks – Sloshing

By SiemensPLM

Fluid sloshing occurs when a change in momentum causes the spontaneous displacement of a fluid.  This displacement can occur within the confines of an enclosure or receptacle – like when you walk a half empty bottle of your favorite Cabernet Sauvignon from your kitchen to the dinner table.  Alternatively, the fluid can be displaced out its container – your non-fat latte splashing out of its cup as you slam on the brakes (and curse out loud) in an emergency.

Understanding sloshing behavior can be quite important.  Not so much for purveyors of fine wine or espresso coffee, but for individuals engaged in the development of mobile containment solutions.  A good example is a fuel tank.  Consider what might happen as you take a sharp corner or hairpin turn in your automobile, while there is very little fuel left in the tank.  Could the fuel pump starve and experience cavitation?  Could you lose power and rapidly decelerate?  These are all potential failure modes that needed to be addressed during the development of the vehicle’s fuel system.   A major aspect of developing dependable products for market is asking yourself over and over again the simple question ‘how can I fail?’  Engineers that considered the scenario above might have massaged the shape of the fuel tank, changed the placement of the fuel pump, or added baffles to the design to avert a potential failure.

Fuel Tank

Modeling sloshing accurately requires a good understanding of the types of fluid that make up the domain (gasoline and air in the example above), and the nature of the excitation the system is exposed to (acceleration history).  Once you’ve buttoned those down, simulating sloshing with NX CAE is straightforward and painless.  The following clip illustrates just that:


I hope you found that useful.  Stay tuned for more tips & tricks, and a sneak peak of what’s in store for NX 8.5


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This article first appeared on the Siemens Digital Industries Software blog at