AVL FIRE? M - Latest Advances in Embedded Body Technology

Every Saturday, Thomas G. and Michael Bambula are excited to bring the developers on stage and provide you an extended read into various simulation topics.

by Zoran Pavlovic , Wilfried Edelbauer & Branislav Basara

One of AVL FIRE? Ms biggest strengths is the embedded body (EB) approach. There are numerous applications that make use of it to get the optimum performance e.g., external car aerodynamics, gearbox, crankcase, moving valves.

One example is shown in?Figure 1: a water pump predicted by embedded body (EB) approach.

Figure 1:?Pressure field inside water centrifugal pump, shown in two different cuts (top row – Z-cut, bottom row – Y cut). Embedded body on refined mesh.

FIRE M also provides a ‘movement preview’ feature which is very useful for all applications that include moving embedded bodies. In the Embedded Body table toolbar, you can find a the button "Movement Preview". Note that the Movement Preview dialog is not modal, which means that, while it is active, the rest of the GUI can be used. This is practical, since while animating the motion, the 3D Viewer is available (e.g. to adjust the view, zoom in or out, etc.). Also, you can edit the defined movement types in their respective dialog, and the motion previews shall be updated automatically.

Another interesting feature is the ‘wall adhesion`. The model for an important physical phenomenon which determines the amount of liquid sticking to solid surfaces is available for Embedded Body as well. This might have a significant effect on heat transfer calculation for some applications, like for example torque or power loss prediction in gear box etc. The behavior of liquid droplets sticking on the solid wall, hydrophobic or hydrophilic, can be defined via the Wall Contact Angle. Differences in the results obtained with and without such model are visible in Figure 3.

Furthermore, with regards to heat transfer capabilities one can define face selections on the embedded body surface, called “Embedded Solid Interfaces”, for which individual surface heat sources and thermal contact resistance can be specified (see Figure 4). Also volumetric heat sources applied on the whole embedded solid can be specified. This allows simple modelling of friction heat losses created in the wall contact area of moving bodies, e.g. in clutches, gear teeth, etc.

Lagrangian Spray in conjunction with Embedded Body ?

The models which are related to Lagrangian spray calculations are able to account for static or moving embedded surfaces within the finite volume computational grid. For the liquid and solid particles the position and the orientation of the embedded body surface are correctly accounted for. Heat transfer which takes place during the contact of spray particles and the embedded body is also considered.

General Wall Boiling Model Supported for Embedded Body

The general wall boiling model is a powerful phase change model which considers several boiling regimes for heat transfer prediction. To reduce the preprocessing effort, the general wall boiling model is also supports embedded solids. The user can directly load the embedded solid surface into a (simple) container mesh, set up the general wall boiling model for the embedded solid and perform the boiling simulation. This reduces the preprocessing time from hours (or days) to several minutes. Although the predictivity of the heat transfer is a bit lower than for the body-fitted simulation, this approach can be used in good manner for estimations of the cooling/heating behavior in thermal management problems with phase change at the wall, as shown in?Figure 6.

Mass Sources for Embedded Bodies

Mass (or species) sources at embedded body selections specified at the “Embedded Solid Interfaces”, as shown in?Figure 4 is another feature to look closer at.?Sources from specific face selections located in the embedded solid interfaces can be used as inlet conditions of type mass flow and velocity inlet. The idea is that these embedded solid interfaces behave similarly to the usual inlet boundary conditions.?An application example is the crankcase flow in Multiphase. For example, oil dripping from piston surface holes is a key issue. By addressing the piston as an embedded solid and these holes as embedded solid interface inlet selections, the mass source feature can be used to simulate the oil leakage. The same applies for piston blow-by, which can be represented as gas phase and species mass source on the embedded solid interface.

Embedded Body for Melting Process

This feature is aimed at thermal runaway applications. The embedded body can be used to represent the meltable part(s), where the embedded body approach should lead to the more realistic prediction of the heating-up process. Once the melting temperature is reached, the material/body starts to melt and disintegrate The figure below illustrates the melting of a battery cap when it is impinged by the jet of hot gases emerging from the battery cells during a thermal runaway event.

Embedded Body for Flow at High Mach Number

The embedded body method can be used for sub- and super-sonic flow applications, e.g. the opening and closing of a gas valve.?Figure 9?shows the pressure and velocity field of a Hydrogen valve. The container mesh is a poly-mesh. Species transport and adaptive mesh refinement (AMR) is enabled. MPI load balancing during the AMR procedure further reduces the simulation time.

As much as we love to nerd out about simulation and read lengthy articles about it, we have to cut it short at this point.

We want to thank Zoran Pavlovic , Wilfried Edelbauer & Branislav Basara for the insights and the impressive work that is performed day to day behind the scenes.

Real-world activities and their real-time limitations bring this Simulation Saturday to an end, but stay tuned for another one soon!

Cheers, Thomas and Michael

What’s next:

You tell us!

• Which simulation topic are you particularly interested?
• What features would you love to see?
• What do you love or hate most about the tool(s) you use?

We love to hear all of it in the comments and encourage you to: - learn more on our product sites:?AVL Advanced Simulation Technologies Tools - try it:?Rescale - simulate for free via?AVL University Partnership Program as a student and academic researcher. - get in contact via [email protected] and [email protected]