Introduction

F-16 is widely used to study the effects of aircraft's performance parameters. For this purpose, a scaled variant of the traditional F-16 is used. This model's dimensions are 3.14% of the original model.

One thing to be noted is that since this analysis is considering the engine intake area as a straight wall, this increases the drag coefficient of the plane overall. An approximation can be made to avoid this. First is to remove the drag created by this area. Alternatively, the same straight wall can be converted to a more tapered surface. This helps to mitigate the effects of the drag produced by this approximation. I, however, haven't taken this into account.

Another thing to note is that this is just a demonstration of how a real simulation can be performed on a real scale model. Also, the lift and drag coefficients can be determined in a similar manner. This model, however, doesn't contain a real F-16 airfoil.

Setup and Meshing

Initially, the boundary conditions of the analysis need to be known. In my case, I am performing a subsonic analysis on the system at 150 m/s (around M=0.3). The meshing has been performed inside ICEM CFD. General Meshing parameters are:

Topology = 0.0001m

Single curve cleanup = 0.0002m

The wall parameters have been chosen as:

y+ = 1

Initial layer height = 1e-6 m

Characteristic length ~ 88 mm

The Initial layer height is the ratio of 0.37x and Reynolds Number raised to the power 0.2, where x is the characteristic length of the airfoil. In this case, the MAC of the airfoil should be preferred as the characteristic length of the whole model. The number of layers is determined from within the software itself.

Setting up an appropriate value of boundary layer and prism layer is very important in getting a proper value from the simulation. Without this, the wall shear stresses and other turbulence parameters cannot be accurately captured from the wall, which give rise to inaccurate results throughout the analysis.

Fluent Settings

With SST K-Omega and Energy methods on, along with Sutherland viscosity selection and ideal gas behavior of air, the pressure farfield setting has been chosen for defining the model at Mach 0.3 (~150m/s). Courant Number was initially set at 50 while increasing it to 80 eventually. Same was done with Momentum, Pressure, Density, and Energy relaxation factors. These should be eventually increased when continuity residual is observed to be increasing in the solver, but since this is just a demonstration, this step was skipped.

Conclusion

Since this is only done for demonstration, and the model doesn't contain an accurate airfoil, this setup provides a basic overview of how such a simulation should be carried out.