On the turbulence amplification in shock-wave/turbulent boundary layer interaction: Direct Numerical Simulation of an oblique shock-wave/flat-plate boundary layer interaction at Mach 2.25.
Check out the publication:
Fang, J., Zheltovodov, A. A., Yao, Y., Moulinec, C., & Emerson, D. R. (2020). On the turbulence amplification in shock-wave/turbulent boundary layer interaction. Journal of Fluid Mechanics, 897.
Credit: Jian Fang (Daresbury Lab, UK)
Check out the publication:
Fang, J., Zheltovodov, A. A., Yao, Y., Moulinec, C., & Emerson, D. R. (2020). On the turbulence amplification in shock-wave/turbulent boundary layer interaction. Journal of Fluid Mechanics, 897.
Credit: Jian Fang (Daresbury Lab, UK)
Direct numerical simulation of a highly forced turbulent fountain
Credit: Jingzi Huang (Imperial College London, UK)
Credit: Jingzi Huang (Imperial College London, UK)
High-fidelity turbulence simulations are performed in a part of a heat exchanger tube bundle. The development of the flow is shown for 4 meshes of increasing size, each of the simulations being run using an optimal number of processors for the CFD software Code_Saturne on ARCHER. The 4 animations that make the full video are obtained from frames generated on the fly by an in-situ visualisation library (Catalyst) coupled with Code_Saturne. The largest simulation (bottom right animation) deals with an extremely large mesh of about 3.4 billion cells, and is performed using about 90% of the full ARCHER (98,304 processors/4,096 nodes). The 151 generated frames amount for about 50 megabytes of data. In comparison, traditional postprocessing relying on dumping data on disk would require about 4.5 terabytes of data, making them nearly impossible to be dealt with. ffmpeg is used to generate the final video.
Credit: Charles Moulinec (Daresbury Lab, UK).
Credit: Charles Moulinec (Daresbury Lab, UK).
To benefit from Code_Saturne's excellent performance and scalability, and to reduce the time to solution, a flow field converter between OpenFOAM and Code_Saturne is used, based on the MEDCoupling tool. Its effectiveness is shown in the case of the PitzDaily Tutorial of OpenFOAM (Steady turbulent flow over a backward-facing step). The left video shows the flow development using OpenFOAM on a coarse mesh (2-D, 13,785 cells). Code_Saturne's meshing tools are used to generate a 7M cell mesh (3-D) from the original one, and the last flow field obtained by OpenFOAM is interpolated onto the new mesh, the simulation being continued using Code_Saturne from there. The right video clearly shows much more unsteadiness, thanks to the mesh refinement and the 3D nature of the simulation. It means that it is possible to start a simulation with one of the two solvers and to continue it with the other one.
Credit: Charles Moulinec (Daresbury Lab, UK).
Credit: Charles Moulinec (Daresbury Lab, UK).
Deskos G., Laizet S., & Palacios R. WInc3D: A novel framework for turbulence-resolving simulations of wind farm wake interactions, Wind Energy, 23, 779-794, web link, PDF
Deskos G. Laizet S., Piggott M.D., Turbulence-resolving simulations of wind turbine wakes, Renewable Energy, 134, 989--1002, web link, PDF
Deskos G. Laizet S., Piggott M.D., Turbulence-resolving simulations of wind turbine wakes, Renewable Energy, 134, 989--1002, web link, PDF
When a body is submerged into a moving fluid, a wake forms. The nature of the wake can affect the body's aerodynamics, structural integrity and the generated noise. Over the last 60 years, axisymmetric wakes have been generated using axisymmetric bodies, such as disks, spheres and bodies of revolution, and key parameters such as the drag coefficient, shedding frequency and similarity and scaling of the wake width and velocity deficit have been documented and verified by numerous experimental and numerical studies. However, asymmetric fractal plates have recently been used to generate axisymmetric wakes. These multiscale wake generators provide a new way to investigate turbulent wakes by exciting several scales and weakening the vortex shedding phenomena. The aim of this video is to illustrate some key characteristics of fractal-generated wakes by mean of comparisons between Direct Numerical Simulation visualisations and wind-tunnel measurements. See Non equilibrium scalings of turbulent wakes M. Obligado, T. Dairay, and J. C. Vassilicos Phys. Rev. Fluids 1, 044409 and Dairay T. & Vassilicos J.C. Direct numerical simulation of a turbulent wake: the non-equilibrium dissipation law, Int. J. of Heat and Fluid Flow, 62(A), 68-74 for more details. Credits: Thibault Dairay, Martin Obligado and Christos Vassilicos.