First, you are asked to carry out a detailed CFD analysis to establish the magnitude of the aerodynamic forces on the van. Next, you are asked to investigate the aerodynamic effects when a box trailer is attached to the van. Finally, you are asked to attempt to improve the aerodynamics of the trailer and assess the magnitude of the improvements you have achieved. PART 1: CFD ANALYSIS OF VAN A Solidworks ASSEMBLY file for a simplified model of the van: van_24nov2011.SLDASM Together with all associated files is supplied in the Module Information folder on Study Space in the folder of van model CAD files. All files in the folder should be copied to your own file space before beginning any work. 1. Carry out an external CFD analysis of the van using SolidWorks Flow Simulation and find the drag and lift forces at a speed of 70 mph, (31.293 m/s), in air at 20 °C. In carrying out this work, choose and justify your choice of suitable flow domain and road surface dimensions, set suitable boundary conditions to correctly simulate the van surface, (hydraulically smooth, Roughness: 0 micrometre); the roadway, (Roughness 5 (mm) or 5000 micrometre); and select appropriate force goals for the calculation. To check for mesh sensitivity, you should carry out CFD solutions at three different, (increasingly-refined), mesh settings. One of the solutions should be at mesh setting 3. The two remaining mesh settings are for you to choose, depending on the complexity of your model. In all cases, the minimum gap size should be set to 0.3 (m). Sufficient iterations should be carried out at each mesh setting to ensure that the solution has converged. It is recommended that the solution should be continued until 1.5 travels of the solution domain have been completed. The number of iterations per travel will depend upon the mesh size and the dimensions of the solution domain. (NOTE: There is a limit in SolidWorks Flow Simulation on the number of elements or cells which can be used. The sum of the fluid and partial cells should not exceed 500,000 or the analysis may fail.) 2. Produce evidence of the progress of each of the three solutions towards convergence by obtaining screen shots of a suitably-rescaled Goal Plot for each mesh setting. 3. Following solution convergence, provide a fully-detailed Surface Parameters report at each mesh setting to confirm your converged solutions for the drag and lift forces on the van. These should be obtained on completion of each analysis and should show the number of iterations completed 4. Tabulate your results from the three solutions, and plot graphs of the drag and lift forces (y-axis) against the average element volume (x-axis) based on those results. An estimate of the average element volume may be obtained by dividing the flow domain volume by the number of fluid elements used. Comment on the graphs and make an estimate of the drag and lift forces on the van at 70 (mph). 5. Using your converged solution at the most refined mesh setting, illustrate the general flow field around the van and highlight any problem areas or interesting flow features using combinations of appropriate Cut plots, Vector plots, Flow trajectory plots or Surface plots. These plots should be produced IN COLOUR. No more than six images should be provided and each one should be annotated to indicate any flow features of interest. Calculate the propulsive power absorbed in overcoming the drag force on the van.