[JamesR]

Hello all

For my master's thesis I am analysing the aerodynamics of a motorcycle using CFD simulations in OpenFOAM. I intend to use an open circuit wind tunnel experiment as well as literature that I have found for the drag and lift coefficient of this motorcycle to validate a CFD simulation with an appropriate turbulence model.

The apparatus in the wind tunnel includes a 3D printed 30 percent scale model of a motorcycle with the rider, a force balance measuring lift, drag and the pitching moment, and a 'splitter plate' to restart the boundary layer upstream of the motorcycle.

The length of the test section is 2 m long by 1.4 m wide by 1 m high. The length of the scale model is about 0.73 m long and will sit roughly in the middle of the test section. I have kept the solid blockage ratio below 10 percent and I should hopefully be able to achieve 70-90 m/s in the wind tunnel.

My plan is to simulate the wind tunnel experiment with all the apparatus inside and compare the lift and drag coefficient data obtained for the motorcycle in the simulation and the results of the force balance measurements to validate the CFD turbulence model and solver. I then plan on remeshing the same motorcycle at full scale to draw conclusions on some of the aerodynamics.

My questions are:

Is my approach for the validation of the CFD simulation correct?
Do I have to simulate the whole wind tunnel or can simulate just the test section and what boundary conditions should I use for the inlet and the outlet?

I have used a hot wire anemometer to measure the 2D planar velocity profile in the wind tunnel just after the settling chamber without the motorcycle apparatus in, however I was not able to measure all the way into the boundary layer so I do not know the full velocity profile.

Any advice would be greatly appreciated

[amirhosseintaran]

Hello,

Is my approach for the validation of the CFD simulation correct?
Do I have to simulate the whole wind tunnel or can simulate just the test section and what boundary conditions should I use for the inlet and the outlet?

Yes, This is correct. Try to start with smaller section of your experiment. for boundary conditions of the Inlet, you can go with inlet velocity and zeroGradient on pressure,
and for outlet both of them should be ZG.
Also try to calibrate the BC based on the governing equations and what's happening during the experiment. this is the general rule of numerical simulation.
Also, you can start with uniform values for inlet velocity, however its not recommended to use uniform distribution, but this can be added later based on an accurate estimation of velocity profile at inlet boundary.

Bests,
Amirhossein.