In many practical circumstances in aeronautical engineering and in related industries, flows arise where concentrated streamwise vorticity is embedded within a turbulent shear flow. The juxtaposition of these features makes such flows particularly challenging to compute using CFD methods. In particular, one may be forced to abandon strategies for modelling the turbulent stresses that prove adequate in two dimensional shear flows (i.e. in flows where the vorticity vector is orthogonal to the mean velocity). The paper reviews developments in modelling turbulent stresses from their transport equations (rather than by appeal to an eddy viscosity hypothesis) and demonstrates, by way of a range of examples, the capabilities of this approach for handling flows with concentrated streamwise vorticity.

A rigid, 55° sweep, half delta wing has been oscillated in pitch at subsonic speeds, and the unsteady pressures on both the upper and lower surfaces recorded for pre-stalled conditions. The oscillations were of low amplitude and at frequencies equivalent to a typical wing first bending mode for full scale applications.

When compared to a quasi-steady approximation, the unsteady pressures on the upper surface of the wing lag the steady case along the line of the primary attachment. The lag represents a constant convective time from the leading-edge with increasing frequency of oscillation. A further localised area of lagging flow is observed beneath the vortex burst point, the location of which is a function of mean angle of attack.

The magnitude of the unsteady pressure variations was seen to increase linearly with the amplitude of the pitching oscillation while the phase lag was seen to increase linearly with frequency parameter.

At a sufficiently high Reynolds number small separation bubbles, as for example at the leading-edge of an aerofoil, are characterised by laminar flow separation and turbulent reattachment. The transition to turbulence in the separated-flow region through the introduction of a disturbance at the boundary, localised in time and space, is examined. It is found that transition to turbulence is promoted by rapidly growing convective instabilities, and not an absolute instability at the point of application of the disturbance.

The equivalent continuum beam-rod model of an aircraft wing structure with composite laminated skins has been developed based on the concept of energy equivalence. The equivalent structural properties of the continuum beam-rod model are obtained by directly comparing the reduced stiffness and mass matrices for a typical segment of aircraft wing with those for a finite element of continuum beam-rod model. The finite element stiffness and mass matrices are condensed through the well known finite element formulation procedure to be used in calculating the reduced stiffness and mass matrices for the aircraft wing segment in terms of the continuum degrees of freedom introduced in this paper. The present method of continuum modelling may yield every equivalent structural property including all possible couplings between bending, torsional and transverse shear deformations. To evaluate the equivalent continuum beam-rod model developed herein, the free vibration and aeroelastic analyses for a box-beam type aircraft wing structure have been conducted by using the continuum beam-rod model, and the numerical results are compared with the results by using other different models of the aircraft wing structure.