In this paper, a new transport equation for the intermittency factor is proposed to model the transition flows. The intermittency behaviour of the transition flows is incorporated into the differential methods for solving the boundary-layer equations, which deal numerically with the basic partial differential equations. The present model accuracy and validity have been tested against a series of recent published experiments, for low Reynolds number, including flows with different freestream turbulence intensities and different pressure-gradients, such as aerofoil and flat plate flows. A comparison of the present method and two different prediction techniques is also given.

The significance of the proposed transport intermittency equation is to reproduce the streamwise variation of the intermittency factor in the transition zone. This method is found suitable and reliable to predict flows with positive or favourable pressure-gradient cases and with turbulence intensity level up to 6%.The method also confirmed the importance of estimating the start of transition, present formula. The present formula is suitable and straightforward to use. For all test cases good agreement between the computed results and the experimental data are observed.

A detailed numerical study has been performed to investigate the origin and mechanism of the formation of windward shocks that have been observed on inclined slender bodies at supersonic speeds inside the bow shock wave around the body. It is shown that the feature is associated with the virtual double cone-like deflection of the supersonic stream by the primary vortices and, as such, can be named the ‘vortex shock’.

Customers demand reliable products and such demands are reflected in the product specification and requirements documents. Indeed, contractual obligations are being introduced to ensure that the supplier meets the cost of unreliability. Thus, equipment suppliers must design products to perform reliably for the required product life. Moreover suppliers must provide sufficient evidence that their product will meet reliability requirements. This evidence is termed the reliability case. The main instigator for the use of the reliability case is the British Ministry of Defence (MoD) under the guise of Defence Standard 00-42 Part 3 but the concept is also becoming accepted in the commercial field as one of the key criteria for selecting products.

This paper describes the work carried out under a collaborative project funded by the UK Department of Trade and Industry (CARAD) entitled reliability enhancement methodology and modelling (REMM). More specifically it will concentrate on demonstrating the methodology in the form of providing the necessary guidance for building a reliability case. It will also discuss the challenges associated with design for reliability and demonstrate how the REMM tool will encourage designers to consider what might go wrong.

The REMM tool encompasses a reliability assessment model and this paper will describe and discuss the advantages of this Bayesian model with particular reference to decision making aspects duringthe design stage of a project.