Title of article :
Instability and Mixing in a Small Estuarine Plume Front
Author/Authors :
M. Pritchard، نويسنده , , D. A. Huntley، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2002
Abstract :
Detailed field observations at the front of a small tidally modulated radial river plume have been carried out to study the
localized internal instabilities thought responsible for mixing. A novel ship-borne instrument array was used to resolve
internal features inside the spreading plume down to horizontal length scales of less than 0.25 m within the top 4 m of the
water column. Results from this study, that applied stringent correctional and filtering procedures to the field data,
identify the presence of multiple internal hydraulic jumps on the plume interface some 30–40 m behind the main plume
frontal discontinuity. This region of instability (Fri >1) corresponds to the rear of a gravity head current. Bulk-mixing
characteristics in the frontal region of the plume were quantified through methods originally applied to laboratory models
of gravity current mixing and also used to represent the extent of turbulent mass and momentum exchange in frontal
boundary conditions of numerical models. Results from field experiments suggested that mixing in the plume front was
modulated by the tidal outflow from the estuary and across-frontal velocity. The ebb tidal mean magnitude of the bulk
frontal mixing coefficient, , was more than double (0·37) that computed from previous analogous laboratory experiments
but of the same order of magnitude as recent small-scale river plume frontal studies.
Keywords :
bulk-mixing coefficient , Froude number , gravity head current , plume front , Teignmouth
Journal title :
Estuarine, Coastal and Shelf Science
Journal title :
Estuarine, Coastal and Shelf Science