Offsprings of a point vortex

The distribution engendered by successive splitting of one point vortex are considered. The process of splitting a vortex in three using a reverse three-point vortex collapse course is analysed in great details and shown to be dissipative. A simple process of successive splitting is then defined and the resulting vorticity distribution and vortex populations are analysed

Vortex merger near a topographic slope in a homogeneous rotating fluid

This work is a contribution to the PHYSINDIEN research program. It was supported by CNRS-RFBR contract PRC 1069/16-55-150001.The effect of a bottom slope on the merger of two identical Rankine vortices is investigated in a two dimensional, quasi-geostrophic, incompressible fluid. When two cyclones initially lie parallel to the slope, and more than two vortex diameters away from the slope, the critical merger distance is unchanged. When the cyclones are closer to the slope, they can merge at larger distances, but they lose more mass into filaments, thus weakening the efficiency of merger. Several effects account for this: the topographic Rossby wave advects the cyclones, reduces their mutual distance and deforms them. This along shelf wave breaks into filaments and into secondary vortices which shear out the initial cyclones. The global motion of fluid towards the shallow domain and the erosion of the two cyclones are confirmed by the evolution of particles seeded both in the cyclone sand near the topographic slope. The addition of tracer to the flow indicates that diffusion is ballistic at early times. For two anticyclones, merger is also facilitated because one vortex is ejected offshore towards the other, via coupling with a topographic cyclone. Again two anticyclones can merge at large distance but they are eroded in the process. Finally, for taller topographies, the critical merger distance is again increased and the topographic influence can scatter or completely erode one of the two initial cyclones. Conclusions are drawn on possible improvements of the model configuration for an application to the ocean.PostprintPeer reviewe

Public Duty and Private Prejudice: Sexualities, Equalities and Local Government

Rather than critiquing social institutions and practices that have historically excluded lesbians and gay men, as did earlier social movements in the 1960s and 1970s, since the 1990s the politics of sexuality has increasingly been about demanding equal rights of citizenship. These citizenship demands have, at least to a degree, been answered via a raft of recent legislation in the UK including the Adoption and Children Act 2002, Employment Equality (Sexual Orientation) Regulations 2003, Gender Recognition Act 2004 and the Civil Partnership Act 2004, and by associated changes in policy making and practice that emphasize ‘Equality and Diversity’. In this article we consider how the implementation of sexualities equalities policies is related to processes of privatization and individualization. This is illustrated by using sexualities equalities work in local government as a case study to indicate how processes of change and resistance are aided by these processes. The article draws on findings from a study of lesbian, gay, bisexual and transgender (LGBT) equalities initiatives in local government in England, Wales and Northern Ireland, which examined the views of those who now have a public duty to implement recent legislative and policy shifts and are obliged to develop equalities initiatives concerning ‘sexual orientation' and ‘gender reassignment’