Coming up

DateNameSpeakerAbstract

12 Dec 2018 

Emily Dieu Internal  

16 Jan 2019 

Sonja Eichentopf Internal  

23 Jan 2019 

David Parker External  

Past

DateNameSpeakerAbstract

17 Oct 2018 

Vishnu Nair Internal Subsiding shells in shallow cumulus clouds: a DNS study
Clouds involve processes extending over a large range of spatial and temporal scales which makes numerical simulation and modeling a formidable challenge. In this study, the dynamics of a subsiding negatively buoyant layer of air at the edges of actively growing shallow cumulus clouds is investigated. I will be presenting the results obtained from direct numerical simulations of a small region at the edge of a shallow cumulus cloud.

24 Oct 2018 

Emily Kruger External From the Enviromental and Industrial Fluid Dynamics research group from the University of Cambridge
Downdrafts and cold pools are convective features of severe storms characteristic of monsoon rainfall. Cold pools in particular contribute greatly to the regeneration of such storms. However, in current weather prediction models both downdrafts and cold pools are poorly paramaterized

Laboratory experiments are performed using finite releases of dense fluid from cylinders of varying lengths. Using a novel extension of the dye attenuation measurement technique to track the edges and centre of mass of the release we can find the velocity and radius of the descent and gravity current after impact. In doing so we are able to model the development of the shape and dynamics of a release in order to inform a model for the gravity after impact.

31 Oct 2018 

Johanna Mader Internal Exploring the mean flow topology between distributed and isolated line sources of buoyancy
I will present results from the direct numerical simulation of a box heated by a combination of localized line sources and homogeneously distributed sources. Whilst plumes driven by localized sources and the convection resulting from homogeneously distributed source are widely studied, their combination has received relatively little attention. Yet, heterogeneously distributed heating is frequently encountered in many practical problems such as temperature control in buildings.  We explore configurations with different ratios of heating contribution from the localized and the distributed sources and develop a model to predict the temperature structure in the domain.

14 Nov 2018 

Younmo Lee Internal Wave impact loading on a floating body
Wave impact has been an important issue in the offshore and shipbuilding industries. In this study, non-linear wave scattering and a phenomenon as similar as Mach stem, which is considered as the primary reasons for accidents due to unexpected wave impact, are investigated. I will present results of OpenFOAM simulations and preliminary experiments about a fixed simplified FPSO, and results of OpenFOAM simulations about Mach stem.  

21 Nov 2018 

Rakib Hossain Internal Reconstruction of flow field from wall thermal imprints
In this talk, I will present the flow decomposition techniques, such as, POD to estimate velocity field. I will explain the POD technique for 'gappy' problem, and the challenges of the reconstruction techniques when the available measurements (wall thermal imprints) are limited.

28 Nov 2018 

Dr Vanessa (Vasiliki) Katsardi External Wave trapping
An array of structures is potentially a wave trapping configuration, which is connected mainly i) with sharp amplifications in all modes of hydrodynamic loading (both forces and moments) and ii) strong free-surface elevations in the liquid regions between the cylinders and on the cylinders’ surfaces accordingly. The above points are directly related to the design of offshore structures (air-gap problem) but also the effective design of wave energy converters.

The presentation will visit the work that has been done by researchers on the field of wave trapping and will focus on arrays of elliptical cylinders, which in accord with arrays of circular cylinders, are potentially a wave trapping configuration. In particular, the purpose of the study presented is the investigation of the hydrodynamic interactions induced by arrays of elliptical cylinders subjected to regular waves with particular interest given in wave-trapping effects.

The solution methodology employs linear potential theory and is based on pure analytic considerations. The interaction phenomena are approached by the use of the Mathieu functions addition theorem. A linear matrix equation for the calculation of the expansion coefficients of the diffraction component(s) is used accordingly to trace the wavenumber(s) under which trapped modes may be stimulated to induce wave trapping in the array and reduction of the energy radiated to the far-field making thus possible to exploit the huge wave potential trapped in a confined liquid region.