Modelling of saline intrusion in marine outfalls

Since their introduction in the 1950s, marine outfalls with diffusers have been prone to saline intrusion, a process in which seawater ingresses into the outfall. This can greatly reduce the dilution and subsequent dispersion of wastewater discharged, sometimes resulting in serious deterioration of coastal water quality. Although long aware of the difficulties posed by saline intrusion, engineers still lack satisfactory methods for its prediction and robust design methods for its alleviation. However, with recent developments in numerical methods and computer power, it has been suggested that commercially available computational fluid dynamics (CFD) software may be a useful aid in combating this phenomenon by improving understanding through synthesising likely behaviour. This document reviews current knowledge on saline intrusion and its implications and then outlines a model-scale investigation of the process undertaken at Queen's University Belfast, using both physical and CFD methods. Results are presented for a simple outfall configuration, incorporating several outlets. The features observed agree with general observations from full-scale marine outfalls, and quantify the intricate internal flow mechanisms associated with saline intrusion. The two-dimensional numerical model was found to represent saline intrusion, but in a qualitative manner, not yet adequate for design purposes. Specific areas requiring further development were identified. The ultimate aim is to provide a reliable, practical and cost effective means by which engineers can minimise saline intrusion through optimised outfall design.

Reduction in gingival overgrowth associated with conversion from cyclosporin A to tacrolimus

Background: Unsightly gingival overgrowth affects many individuals immunosuppressed with cyclosporin A (CsA), Current management involves repeated periodontal surgery and intensive hygienist support. Tacrolimus is an effective alternative immunosuppressive agent for renal transplantation which does not appear to produce gingival enlargement.

The calcium channel blocker used with cyclosporin has an effect on gingival overgrowth

Background/aims, To investigate whether the choice of calcium channel blocker, used in conjunction with cyclosporin A, affected the prevalence of gingival overgrowth.

The effect of rudder angle on the scouring action produced by the propeller wash of a manoeuvring ship

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