Turbulence is one of the greatest challenges for fluid mechanics and physics. Indeed, turbulent flows are all around us, from the flow of air over an aircraft or car, to the ocean’s currents. Whilst the Navier-Stokes equations exactly represent the flow of a fluid, the solution of these non-linear equations for turbulent flows requires a numerical approach, often using High Performance Computing. These approaches for solving the Navier-Stokes equations, collectively often known as Computational Fluid Dynamics (CFD), have revolutionized the engineering design process, reducing the need for experimental studies and providing greater insight into the flow physics.
However for many flows of practical engineering interest, such as those in the aerospace or automotive sectors, the solution of the exact Navier-Stokes equations is not possible due to the requirement to resolve all scales of turbulence, which requires computational resources larger than what is available with the current generation of computers. To overcome this difficulty, ‘turbulence models’ are used to approximate the effect of some, or all of the turbulent scales on the flow itself. The derivation of these turbulence models has been the focus of intense research for more than 60 years and has possibly one of the greatest affects on the accuracy of a CFD simulation.
This talk will focus on the suitability of these turbulence models for some of the grand challenges of modern day CFD, in particular how we can use CFD to design modern day aircraft and cars entirely in the virtual domain. The performance of a range of turbulence models is discussed on fundamental and real-life applications, and suggestions for new models are brought forward.
Ultimately achieving the goal of an entirely virtual design process could revolutionize the way engineering design is conducted, but many challenges lie ahead before this can be made possible.