3 papers
physics.flu-dyn2024
Modelling visibility and surface deformation in particle-fluid flow fields generated by helicopter rotors
Stephen Langdon, David J. Needham
As a helicopter descends towards a bed of sand, a high velocity particle laden cloud can form around the helicopter body, a phenomenon known as "brownout", and a consequence of whi…
math.AP2024
KPP fronts in shear flows with cut-off reaction rates
D. J. Needham, A. Tzella
We consider the effect of a shear flow which has, without loss of generality, a zero mean flow rate, on a Kolmogorov--Petrovskii--Piscounov (KPP) type model in the presence of a di…
physics.flu-dyn2024
A mathematical model for wind-generated particle-fluid flow fields with an application to the helicopter cloud problem
D. J. Needham, S. Langdon
We develop a model for the interaction of a fluid flowing above an otherwise static particle bed, with generally the particles being entrained or detrained into the fluid from the…