Week 11- Broadband Noise modelling over Ahmed body

Aim

1. Describe Ahmed's body and its importance.
2. Setup the domain and setup assuming body is travelling at 110 kmph
3. Run the setup till convergence and plot for static pressure and coefficient of drag and lift to check for convergence
4. Turn on Broadband- modelling and detail the acoustic field study over Ahmed body.

Ahmed body

Ahmed's body is a generic form of the car body that resembles all the essential flow features around a vehicle. This generic form was first defined and characterized in the experimental work of S.R.Ahmed. This body allows us to capture all the characteristics features that are relevant to bodies in the vehicle industry. This body can be used for a lot of experiments like calculating the drag and lift which are essential nowadays in the design of car bodies. Also this can be used to capture the wake regions, Flow seperation, vortices etc.. Different slant angles provide different values for Coeffecient of drag.

Setup

• Pressure based steady state simulation
• Material set to air
• Energy equation is turned on
• K-epsilon model is selected
• Velocity inlet with a velocity of 30.55 in x direction
• Pressure outlet
• Road is set to moving wall with a velocity same as inlet
• Coupled method with a courant number of 10
• Coefficient of drag and lift is set to plot
• Simulation is run for 250 iterations
• After running the simulation the acoustic model is turned on

Outputs

Liley's total noise contour

Acoustic power level contour

Static pressure contour

Total pressure contour

Velocity contour

Conclusions

• The surface which produce high noise can be observed through the extracted contours
• The solution are converged well which can be observed through the plots provided
• Aero-acoustic study on the given body is done successfully and it was concluded that the frontal area caused more vibrations