1 st Automotive CFD Prediction Workshop SAE Notchback Test case - PowerPoint PPT Presentation

1 st Automotive CFD Prediction Workshop SAE Notchback Test case Filipe Fabian Buscariolo Walid Hambli James Slaughter Prof. Spencer J. Sherwin

Main Findings • High correlation level for the drag coefficient and pitch moment • Demonstrated downforce increment – consistent with literature for bodies with diffuser • Reproduction of main flow structures

Nektar++ • Bridging the gap – uDNS/iLES simulations – Spectral/hp element method – Flexibility (h) – High-resolution (p)

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Nektar++ - Automotive applications Research in collaboration with

Configurations for spectral/hp element method • Nektar++ - Automotive Pipeline – continuous Galerkin (CG) method – iLES/uDNS • New setup for Spectral Vanishing Viscosity (SVV) – CG method with discontinuous Galerkin SVV kernel • Stable solutions – relatively high Reynolds number flows – fully 3D complex geometries simulations

Test case – SAE Reference Notchback Model • Model considerations – Full domain: 7L – Similar working section • Meshing design – Workshop RANS initial grid High-order surface elements: 6 th order – – Mesh elements: Tets + Prism – DOFs: • P4 ~ N_DOF = 28mill ~ DES • P5 ~ N_DOF = 56mill ~ 2*DES

Configurations for spectral/hp element method • Efficient high-order meshing strategies – high-order mesh design • solution order (P N ) and mesh order (M) – initial sizing – h-refinement zones – relationship between h and p refinement

Workflow Pipeline

Mesh Comparison: RANS vs NekMesh

Results - Coefficients • Solution initialised from RANS • P4: 18 CTUs • P5: 4 CTUs (P4 from the 14 CTU) P5 P4 CL -0.127 Cm -0.082 CD 0.208

Results – Flow structures Contours of velocity magnitude at Y=0 P5 Experiments

Results – Flow structures Contours of U velocity at Y=0 P5 Experiments 0.0

Results – Flow structures Contours of V velocity P5 Experiments

Pressure Coefficient – C P Results

Results – Q-Criterion 350

Main Conclusions • Based on workshop proposed RANS mesh, consistent correlation with drag coefficient • Lift coefficient value follows similar trend of automotive bluff bodies with diffuser – Acceptable correlation with pitch moment • High resolution iLES flow solution would be improved with additional CTUs – Solving turbulent scales

Workshop Conclusions • Boundary Conditions – Experimental Results • More temporal investigation for code validation • Further resources for Higher-Order/ High-Fidelity solutions • Axes orientation

Thanks! www.nektar.info f.fabian-buscariolo16@imperial.ac.uk w.hambli17@imperial.ac.uk j.slaughter19@imperial.ac.uk