79_Transonic Flow

In this post, we will perform a CFD simulation of three-dimensional transonic turbulence.

Transonic refers to speeds that exceed the speed of sound, meaning velocities between Mach 0.8 and 1.2.

 

First, the geometry to be used in the analysis is as follows.

 

ref : courses.ansys.com

 

The description of geometry creation and meshing will be omitted.

 

In the setup stage, select double precision in the launcher settings. Single precision, while less precise, uses approximately half the amount of memory and reduces the size of the generated files, which in turn speeds up the simulation of file processing. More specifically, double precision offers about 16 significant digits and can represent numbers up to 1.8e+308 with a 64-bit value.

Therefore, double precision is advantageous for precise analyses, but single precision is preferable for faster analysis speeds or file generation.

 

 

In the model settings, set energy to on, and use the Spalart-Allmaras for the viscous model. The Spalart-Allmaras is a one-equation turbulence model developed in 1992. The variable of its transport equation is the turbulent viscosity. It is widely used because it can accurately predict values for two-dimensional mixing layers, boundary layers, and wake flows.

 

For the solution method, select the coupled scheme and leave the rest as default settings. Additionally, check pseudo transient and high order term relaxation to stabilize the solution for steady-state and provide faster convergence.

 

The numerical solution is as follows. It pertains to the drag force on the left wing.

 

 

Additionally, not only through graphs, but precise numerical values can also be observed from the consol window.

 

 

 

In CDF-post, the Pressure coefficient contour can be checked, and it is as follows.

 

 

Additionally, contouring the Mach number applied to the wing yields the following.

 

 

The velocity vector at the rear of the wing can be observed.

 

 

The videos provided by Ansys are very specific and detailed in explaining CFD simulations, but there is still much to learn about the theoretical aspects, and more understanding is needed. I believe that more practice will be necessary to freely simulate the tasks I want to accomplish.