LES and DES of high reynolds number wall bounded flows

• High Reynolds number wall bounded flow is here investigated using Large Eddy Simulation (LES), Detached Eddy Simulation (DES) and Reynolds Averaged Navier Stokes (RANS). The first case considered is the fully developed turbulent channel flow at Re, « 395,590,1800 and 10,000. This flow clearly indicates the development of the undisturbed boundary layer and related events, such as streaky structures, hairpin vortices and ejection events. The second case is the flow over an axisymmetric hill in a channel, here the flow contains complex structures such as a turbulent boundary layer with several unsteady separations and reattachments. It is three-dimensional due to both streamwise and spanwise pressure gradients on the lee-side of the hill. The shallowness of the separation region makes the flow a demanding test case for any computational fluid dynamics model. The third case is the flow past an axisymmetric submarine hull with an elliptic forebody and a smoothly tapered stern - the DARPA Suboff model AFF-1. This flow case is highly demanding due to the long midship section, on which the boundary layer is developed, in combination with the elliptic forebody and the tapered stern. Both LES and DES performs well in all cases considered, while RANS has slightly lower accuracy in the channel flow and the axisymmetric hull, and fails to predict some flow features for the axisymmetric hill. Also DES has some problems with the axisymmetric hill case, related to the inlet condition of the modified eddy viscosity.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering (hsv//eng)

Keyword

Complex structures; Computational fluid dynamics model; Streaky structures

Boundary layers; Channel flow; Navier Stokes equations; Pressure gradient; Reynolds number; Turbulent flow

Large eddy simulation

Publication and Content Type

ref (subject category)

kon (subject category)