Abstract Nearshore circulation, produced by a wave‐induced radiation stress gradient, forms different circulation patterns under different wave characteristics and topographical conditions. A more general equation was deduced on the orthogonal curvilinear coordinate system to unify the diversities among related theories and to investigate the nearshore circulation on an arc‐shaped coast. The results show that circulation patterns depend on the flow torque factor which is in turn determined by both the wave characteristics and the topographical conditions. Due to the differences of this torque factor, the straight coast and the arc‐shaped coast will produce different circulation patterns. Key words: nearshore currentsarc‐shaped coast
A depth‐averaged and a three‐dimensional hydrodynamics model were applied in a study to evaluate quantitative methods for characterizing tide and current in one of the major basins of Puget Sound. The objective of the investigation was to assess the models' performance and operational requirements for future management applications. The study found that at the chosen horizontal spatial resolution scale of 762 m, both models were capable of reproducing major observed tide and tidal current characteristics in the study area and the differences between the results of the two models are small. Typical runs of the models with the current resolution require about 6–20 System Resources Units on a CRAY X/MP‐48 supercomputer. For future simulation of general tidal circulation and transport features in the Sound, the use of depth‐averaged models with spatial resolution of 800 m or less is recommended. For certain management problems around the Sound (for example, outfall siting, dredge material disposal) in which more detailed knowledge of the tidal current might be useful, the use of three‐dimensional models with finer spatial resolution (300 m or less horizontally and 15–50 m vertically) is suggested. The study also demonstrated that with increasing availability of computing power, wider use of multidimensional hydrodynamics models for estuarine environmental decision making as well as basic scientific research is very promising.
Abstract Differences in the dispersion and/or catalytic pellet size between laboratory and commercial reactors, operating at the same average residence time, may lead to differences in the yield of a desired product. Bounds are developed for predicting the maximal design uncertainty introduced by these phenomena for a network consisting of an arbitrary number of irreversible first‐order reactions. A major advantage of these bounds is that they do not require any knowledge of the rate constants. It is shown that in a packed‐bed reactor, the fractional yield loss is smaller than: where m − 1 is the number of reaction steps involved in converting a reactant to the desired product, σ is the dimensionless variance of the residence time density function, Bi m is the Biot number, p 2 = [( V p / S x ) 2 (1/ D e τ)], and τ is the average residence time.
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