The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

A hybrid RANS-LES approach with delayed-DES and wall-modelled LES capabilities

Strategies for turbulence modelling and simulations

The numerical simulation of high Reynolds number flows is hampered by model accuracy if the Reynolds-averaged Navier–Stokes (RANS) equations are used, and by computational cost if direct or large-eddy simulations (LES) that resolve the near-wall layer are employed. The cost of a calculation scales like the Reynolds number to the power 3 for direct numerical simulations, or 2.4 for LES, making the resolution of the wall layer at high Reynolds number infeasible even with the most advanced computers. In LES, an attractive alternative to compute high-Re flows is the use of wall-layer models, in which only the outer layer is resolved, while the near-wall region is modeled. Three broad classes of approaches are presently used: bypassing this region altogether using wall functions, solving a separate set of equations in the near-wall region, weakly coupled to the outer flow, or simulating the near-wall region in a global, Reynolds-averaged, sense. These approaches are discussed and their ranges of applicability are highlighted. Various unresolved issues in wall-layer modeling are presented.

Wall-layer models for large-eddy simulations

The Structure of Turbulent Shear Flow By Dr. A. A. Townsend. Pp. xii + 315. 8¾ in. × 5½ in. (Cambridge: At the University Press.) 40s.

/pdf/the-structure-of-turbulent-shear-flow-2yf3szhaqb.pdf

The Structure of Turbulent Shear Flow

The objective of this study was to make use of recent developments in Computational Fluid Dynamics (CFD) modeling to investigate the pressure phenomena and the hypothesized concomitant vein blood flow that take place in the spinal canal during extension and flexion motion of the cervical spine.

/pdf/cfd-modeling-of-pressure-transients-in-the-spinal-canal-2yjfd0f3r5.pdf

Cfd modeling of pressure transients in the spinal canal during whiplash motion – a pilot study

An Investigation of Outlet Boundary Conditions for Incompressible Near Field Acoustics

An experimental study of water transport on a generic mirror was carried out. The experimental set-up was a generic mirror that had a total height of 30 cm and a width of 20 cm with 5 2 holes with a diameter of 1 mm, see figure 1. As the water was introduced, the ambient air formed a rivulet th a raveled towards the trailing edge of the mirror. The rivulet breaks up at the trailing edge or just continuously d rains on the flat side of the mirror. This rivulet will also break up at the end and form droplets whose size depends on the flow rate and the velocity of the ambient flow. The experiment was done at Volvo Car Corporation using three diff rent water flow rates (0.8, 0.5 and 0.2 l/h) and four ambient velocities (11, 14, 19 and 25 m/s). A high-speed camera was used to visualize the water, which contained a fluorescent liquid for easier post processing. Every case w as repeated five times in order to obtain reasonably good statistics for the rivulet path and second-order dropl ets. In this paper we distinguished between moving and non-moving separation of rivulets/films. A moving rivulet i s a rivulet that has a velocity when it breaks up, and a non-moving rivulet is one that does not have any velocity whe n it breaks up. In the latter case it accumulates water at the edge before it breaks up and sheds from the edge. The exper iment shows good agreement with previous separation criteria for moving film. The correlation for the non-moving films resulted in a different correlation as compared to Tivert & Davidson (2010). This discrepancy can be an effect o f errors in the local air velocity estimation or have to do with geometry.

/pdf/experimental-study-of-water-transport-on-a-generic-mirror-hv6ijszs6g.pdf

Lars Davidson

Papers

Cfd modeling of pressure transients in the spinal canal during whiplash motion – a pilot study

An Investigation of Outlet Boundary Conditions for Incompressible Near Field Acoustics

Experimental study of water transport on a generic mirror

High-Lift Airfoil Flow Simulations Using a Two-Layer Reynolds Stress Transport Model

Computational Fluid Dynamics in Ventilation: a new REHVA Guidebook