Comparison of Wind Tunnel Configurations for Testing Closed-Wheel Race Cars: A CFD Study

Combined Aero and Underhood Thermal Analysis for Heavy Duty Trucks

“…Five prism layers with a thickness of 25 mm were used to provide an accurate estimation of the velocity near the wall in high Reynolds number external flows (~5.7E6). Standard wall functions were used by keeping the y-plus value within an acceptable range from 20 to 200 [16].…”

“…A total of four prism layers were selected over the vehicle surfaces with a total thickness of 20mm. In Re-Normalized Group (RNG) k-epsilon turbulence modeling, wall functions are considered to avoid the high resolution at vehicle surfaces [16]. The total number of mesh cells varied from 20 to 50 million, based on number of vehicles and its platooning configuration.…”

“…In the automotive and transport industry, aerodynamic thermal improvements are highly desirable in the design of fuel-efficient vehicles since the expected global fuel consumption to grow at a compound annual growth rate (CAGR) of 2.1 percent over the period 2014-2019 [44]. Over the last two decades, continuous efforts to build aerodynamic designs by modifying external vehicle surfaces and through add-on aerodynamic drag reduction devices are growing rapidly [9,11,16,20]. In transport vehicles, external air-flows are heterogeneous and it can have a positive or even negative impact on both aerodynamics and thermal management, depending on the influence of vehicle traffic and vehicle position.…”

“…The prism layers were used to provide an accurate estimation of the velocity near the wall in high Reynolds number external flows (~5.7E6). Standard wall functions were used by keeping the y-plus value within an acceptable range from 20 to 200 [16]. The overall residuals were dropped by three orders of magnitude using an under-relaxation factor for velocity, pressure, and turbulence parameters (k and ε) considering 0.7, 0.3, and (0.8 and 1), respectively.…”

“…Moreover, the volume controls were selected around the vehicles surface to keep a maximum edge size was up to 40 mm as shown in Figure 7.3(ii). The numerical wind-tunnel dimensions and near wall region turbulence were modeled as suggested by J2966 SAE technical paper [20] and Connor et al [16].…”