## Wildkatze Release 2023.1.1

Wildkatze 2023.1.1 Release Notes

## Flow

NavierStokesExtensionModel : Addition NavierStokesExtensionModel to provide solution to Extended Navier Stokes for solution of flow where Knudson number is greater than 1E-3. Applicable to rarified gases and micro-channel flows.

ViscousFlowModel Addition of ViscousFlowModel for high viscosity flows Navier Slip Wall BC

## Multiphase

Predictor Corrector algorithm to achieve rapid convergence of VOF equations Mass balance: Implicit VOF that runs with large time-step sizes do incurr mass or volume fraction losses. A procedure is added to preserve the volume fraction and masses. With new procedure now the typical mass loses is below 1E-12 percentage. Surface Tension Force New Continuum Surface Force model with better Wall Contact Angle treatment.

## ElectroMagneticModel

Electromagnetic model Electric and Vector potential formulation. Also supports two way MHD.

## Linear Solvers

New AMG solvers for pure Neumann BC problems.

Asynchronous parallel exchanges in AMG for better parallel scaling.

## Wildkatze Innovation

### Highly Robust and Accurate Solver

### Ultra-fast Simulation from Console Command

```
solver.sh -lc flow meshFile -vel 25 -wd -kw -forces -lc pf o.txt -lc iterate 500 -lc export-ensight results
```

- Sets up simulation with inlet velocity of 25 m/sec
- Adds Wall Distance Model and K - Omega Turbulence Model
- Exports Forces
- Performs 500 iterations
- Exports results in Ensight Gold format

As shown above Wildkatze has this unique feature to automatically set up and perform simulations. This makes it extremely easy to use and very useful for Optimization problems.

### Third Order SIMPLE Solver

Wildkatze’s Third Order Flow is the **first Pressure-based SIMPLE implementation** available in commerical softwares. It is **Accurate, Robust and Fast**. It gives same level of accuracy on 10 times coarser mesh resulting in huge saving on simulation time and cost.

### Truely Implicit Interface Tracking Method for Multiphase Simulations

With Wildkatze’s innovative **MaxGBCA** scheme we can track interfaces between phases at **high Courant** numbers without losing accuracy. For very famous Bubble Rise benchmark problem, Wildkatze maintains accuracy at Courant numbers as high as 5 or above.

Innovative approach in setting up physics models | Flexibility in the selection of CFD schemes | Customize the Finite Volume solver | Immersed Boundary Method |
---|---|---|---|

Wildkatze package features a wide range of physics models. In general, the flow field is composed of various physical phenomena and it is difficult to capture all of them with one physics model. Wildkatze has the option to divide the analysis region and set up different physics models. For example, it is possible to set up LES model in one region and k-omega turbulence model in the other region. | When user selects a time stepping or gradient discretization scheme, generally in conventional solvers, the same scheme would be set for the entire simulation. In contrast, Wildkatze allows the user to select different time stepping and gradient discretization schemes for each physics model. | Wildkatze provides the user access to almost all variables and internal solver settings through C++ coding. This flexible customization option empower the user to take control of the solver and customers can incorporate their own physics models into Wildkatze for conducting advanced research. User can also enhance the capabilities of existing physics models through Add Feature option in Wildkatze. | Immersed Boundary model has been implemented in Wildkatze for solving transient and steady fluid-structure interaction problems like rotation, movement etc. The Immersed Region does not need to be moving, it could be stationary and marked once. This makes adding or removing objects from the simulation easy and also support various types of motions, which are difficult to simulate with other mesh motion techniques, like morphing or chimera grid methods. Fast and robust solid marking algorithm in Wildkatze allows the user to use this method without much penalty on simulation time. |

## Applications