The wake of the front tires affects the airflow over the remainder of a fenderless race car. The tires can also be responsible for up to 40% of the vehicle’s drag. Prior experiments have used compromised models with solid, symmetric hubs and nondeformable tires. The present experiment acquires particle image velocimetry measurements around a 60% scale model of a deformable pneumatic tire fitted to a spoked Formula 1 wheel with complete brake geometry and supplementary brake cooling ducts. The results show reversed flow regions in the tire wake, asymmetric longitudinal vortex structures behind the tire, and a tire wake profile that is unlike previous experimental results and postulations. The flow through the hub of the wheel causes a shift of the wake inboard (toward the car) so that the outboard side of the wake does not extend past the outline of the tire.

The flowfield around a 60% scale stationary Formula 1 tire in contact with the ground in a closed wind tunnel at a Reynolds number of 500,000 was computationally examined in order to assess the accuracy of different turbulence modeling techniques and confirm the existence of large scale flow features. A simplified and replica tire model that includes all brake components was tested to determine the sensitivity of the wake to cross flow within the tire hub along with the flow blockage caused by the brake assembly. The results of steady and unsteady Reynolds averaged Navier-Stokes (URANS) equations and a large eddy simulation (LES) were compared with the experimental data. The LES closure and the RANS closure that accounted for unsteadiness with low eddy viscosity (unsteady kω-SST) matched closest to the experimental data both in point wise velocity comparisons along with location and intensity of the strong counter-rotating vortex pair dominating the far wake of the tire.

The flow field around a 60% scale stationary Formula 1 tire in contact with the ground in a closed wind tunnel is examined experimentally in order to validate the accuracy of different turbulence modeling techniques. The results of steady RANS and Large Eddy Simulation (LES) are compared with PIV data-performed within the same project. The far wake structure behind the wheel is dominated by two strong counter-rotating vortices. The locations of the vortex cores, extracted from the LES and PIV data as well as computed using different RANS models, show that the LES predictions are closet to the PIV vortex cores. All turbulence models are able to accurately predict the region of strong downward velociy between the vortex cores in the centerplane of the tire, but discrepancies arise when velocity profiles are compared close to the inboard and outboard edges of the tire, due to the sensitivity of the solution to the tire shoulder modeling. In the near wake region directly behind the contact patch of the tire, contour plots of inplane-velocity are compared for all three datasets. The LES simulation again matches well with the PIV data.

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Water purification is a crucial process in the operation of a municipality. Ensuring that water treatment plants are meeting regulatory requirements is a vital, but complicated and costly process. Because water treatment plant influent and effluent rates are demand driven, and vary both diurnally and seasonally, controlling flow rates for the disinfection stage can be challenging both operationally and economically. Thus, performing large-scale field experiments to verify water quality regulatory criteria such as modal transport time of conservative tracers in a chlorine disinfection contact tank under extreme operating conditions can range from difficult and costly to impossible. In this paper, a computational fluid dynamics (CFD) approach is used to verify the compliance of a water reclamation plant disinfection stage with respect to modal time. CFD allows a large parameter space to be tested without the need to build large physical models or taking functioning systems in a treatment plant offline. This can save facilities large amounts of time and money when designing, optimizing, and developing plants or checking compliance. This paper introduces a hybrid approach of computational analysis of a water reclamation plant's chlorine contact tank in Southern California. The method uses a hybrid approach which combines three-dimensional CFD with hydraulic grade line analysis of the open water surface. Verification cases were compared to experimental measurements at a functioning, full-scale plant with modal contact time differences below 15%. The method was then used to predict residence time distributions (RTDs) for cases which could not be artificially induced at the plant, but represented peak flow conditions that could be expected. © 2018 Water Environment Federation • Practitioner points• The hybrid 3-dimensional CFD method allows low cost simulation of the disinfection stage. • By using head loss calculations to properly define the water level at each section, a steady-state single phase flow simulation can be run in 3D without the need to scale down geometries. • This allows for more accurate transport results and parameter studies. Figure 8. Predicted flow-through curve for hypothetical extreme flow case.