Details of Grant 

EPSRC Reference:	GR/S86303/01
Title:	Improving Physical Models of the Turbulent Boundary Layer.
Principal Investigator:	Nickels, Dr T
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department:	Engineering
Organisation:	University of Cambridge
Scheme:	Overseas Travel Grants Pre-FEC
Starts:	01 December 2003	Ends:	30 November 2004	Value (£):	12,635
EPSRC Research Topic Classifications:	Aerodynamics
EPSRC Industrial Sector Classifications:	Aerospace, Defence and Marine
Related Grants:
Panel History:
Summary on Grant Application Form
Turbulent boundary layers are thin regions of complex flow that occur close to surfaces. It is these regions that determine the skin-friction drag on vehicles and influence the losses inflow machinery such as fans and pumps. In addition, although these regions are normally thin, small changes in the flow can lead to a dramatic phenomenon known as separation which leads, for example, to the stall of aircraft wings and large drops in performance for pumps and fans. Despite the significance of these regions for design of machinery, predicting the behaviour of turbulent boundary layers is still an inexact science. A variety of engineering techniques and methods have been used with varying success. As with any turbulent flow the problem of prediction lies in the non-linearity of the equations of motion. These non-linearities lead to the development of a wide range of different scales of motion in the flow. These may be thought of as complicated threedimensional swirling motions and the range of scales relates to a combination of many such motions:from small rapidly swirling motions to large slowly swirling motions. The range of sizes of these structures increases with a number known as the Reynolds number. Essentially this number increases as either the size or the speed of the flow is increased, or the viscosity is decreased. Most technologically important flows are associated with large Reynolds numbers and hence a wide range of sizes of swirling motions. Solving the exact equations for these flows numerically, then, requires a large domain to capture the large motions, and a fine mesh of points to resolve the smallest motions. Wall-bounded flows are also complicated by the fact that the motions become smaller and more rapid as the wall is approached, hence it is necessary to have a very fine mesh near the wall. As the Reynolds number increases the computational effort increases rapidly to such an extent that it will not be possible to compute the boundary layers in real problems of technological interest using this exact approach for some time.This difficulty has led to the development of a variety computational techniques that overcome this difficulty by incorporating theoretical or empirical models into the procedure. Unfortunately these models introduce new parameters to deal with every different change to the flow conditions. These semi-empirical models do not have a consistent basis and hence it is hard to extend them for new flow conditions. The PI has recently developed a single model that explains and predicts a range of flow changes using a single, universal parameter. The object of this research is to further develop this model and test it against new data in order to increase its range of applicability and accuracy and to combine it with existing models of the outer region of the flow that are being developed by the collaborators.
Key Findings
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Potential use in non-academic contexts
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Impacts
Description This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk Summary Date Materialised
Sectors submitted by the Researcher
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Project URL:
Further Information:
Organisation Website:	http://www.cam.ac.uk