Partially Averaged Navier-Stokes scale-resolving method for complex engineering applications

For a more accurate and practical or affordable representation of turbulence in complex flows, scale-resolving simulation (SRS) methods have emerged as an alternative to the more computationally intensive Large Eddy Simulation (LES). The Partially Averaged Navier-Stokes (PANS) approach formulated by Girimaji et al. 2003 and Girimaji, 2006 is a bridging SRS method. PANS and similar scale resolving methods are very attractive to CFD users, especially those involved in simulations of complex industrial flows. The PANS method seamlessly transitions from the Reynolds-Averaged Navier-Stokes (RANS) to the Direct Numerical Solution (DNS) of the Navier-Stokes equations, depending upon the prescribed cut-off length (filter width), where the cut-off resolution parameters are a ratio of unresolved to total kinetic energy f_k and of unresolved to total dissipation f_e. A principal problem in industrial applications is to obtain the best single run on the given numerical mesh. This means that the resolution parameters must be calculated continuously during the calculations. There are several proposals on how to calculate fk with the formula using the total kinetic energy, as well as a recent approach by Basara, Pavlovic, and Girimaji (2018) in which the resolved component, called the scale supply variable (SSV), is calculated with its own equation. This new PANS SSV variant enables efficient computations of applications with moving geometries, transient boundaries, and inherent instability, e.g., periodic fuel injection. This talk will give an overview of PANS calculations for some very different industrial CFD applications: external aerodynamics, pumps, engine including spray and combustion, both on body-fitted meshes and using the immersed boundary method.