The near-field mixing of effluent from buoyant and nonbuoyant flows from outfalls discharging into a cross-flowing ambient current in trapezoidal channels has been investigated. A physical model was scaled to represent a typical large outfall into one of the connecting channels of the Great Lakes system. The discharged jet was measured in detail to determine the velocity and concentration fields. The excess velocities and concentrations were found to follow the Gaussian distribution. Empirical expressions for the jet trajectories, minimum dilutions, and plume widths were derived. A correction factor has been introduced to the concentration distribution to ensure mass conservation. The calibrated model was verified by comparison with field data and the results of other near-field models (PDS, MIT, and CORMIX).Resume : Le prCsent article rend compte des rtsultats d'une Ctude portant sur le melange en champ proche des effluents de panaches flottants et non flottants provenant d'exutoires se dtchargeant dans le courant transversal ambiant de canaux trapkzoidaux. Un modtle physique i l'tchelle a Ct C construit pour representer un exutoire type de grandes dimensions se dtchargeant dans l'un des canaux de raccordement du rCseau des Grands Lacs. Le jet de dtcharge a fait l'objet de mesures dCtaillCes afin de determiner la vClocitC et les champs de concentration. On a remarqut que les vtlocitts et les concentrations exctdentaires suivaient la distribution gaussienne. Des expressions empiriques ont t t t Clabortes pour les trajectoires des jets, les dilutions minimales et la largeur des panaches. Un facteur de correction a t t t appliqut i la distribution de la concentration afin d'assurer la conservation de la masse. Le modtle ttallonnC a Ct C compart aux donnkes sur le terrain ainsi qu'aux rtsultats d'autres modkles en champ proche (PDS, MIT et CORMIX).

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