Vertical slot fishways allow energy dissipation as a function of the pool, longitudinal slope, baffle and vertical slot design. The mean and turbulent flow patterns in these structures must be compatible with the fish target. The design of these structures is commonly based on previous successful fishways as well as simplified theoretical equations and empirical relationships. To aid in the design of these structures, a three-dimensional hydrodynamic model was used to simulate the flow, and experimental studies were used to validate the model. The mean velocities, pressures and parameters indicative of turbulence were analyzed. The maximum flow velocities were up to 32% higher than the values obtained using a simplified theoretical equation. The evaluation of the volumetric dissipated power indicated that the mean value for the pool was lower than 150 W/m3; however, analysis of the spatial distribution showed that in some areas, the values can exceed 1000 W/m3. The results indicate that the numerical simulation was able to adequately represent the flow considering the computational cost involved. Accordingly, it can be used as a complementary tool for the design of new fishways and for the analysis of modifications in existing ones.

The use of capillary culture chambers as artificial pancreas and artificial liver devices would be aided by an improved ability to control the movement of molecules through the capillary walls. The modeling and analysis of the flow and mass transfer in capillary cell culture chambers in which cultured mammalian cells are grown to form masses with tissue density in the extra-capillary spaces is desirable as a basis for scaleup and optimization of the particular microenvironment. The relative roles of diffusion and ultrafiltration with convection in enhancing mass transfer across the capillary membranes are poorly understood in real cell cultures and the effects on culture viability of flow conditions chosen to promote convective flow across the capillary membranes and through the cultured cell masses are also of interest. In this report, experience with materials and techniques for fabricating capillary culture chambers with a more readily analyzed fully defined regular geometric relationship between 90 to 100 capillaries in a parallel bundle is described. High and low pressure capillaries were interspersed in a regular array. Evidence is presented for retention of cell viability during flow conditions which were chosen to induce convective flow through the cultured cells in such a chamber.

The traditional approach for the hydrodynamic characterization of the flow down stepped spillways is through physical modeling, which is susceptible to scale effects and has limitations related to experimental apparatus, laboratory space and the spatial discretization of data collection. Computational fluid dynamics (CFD) is an important tool for hydrodynamic analysis because, if used properly, it presents great potential for application in hydraulics. In this work, CFD was used to model the skimming flow down a stepped spillway to investigate the effects of possible pressure measurement errors due to uncertainties in the position of the sensors within the steps. The numerical model was validated through literature velocity profiles and pressure experimental data. The results showed that the best values of water fraction (α) to define free surface are α = 0.30 in the nonaerated region and α = 0.10 in the aerated region. Statistical parameters were calculated using experimental data to estimate extreme pressures. These parameters and the simulation results were used to determine that the extreme maximum and minimum pressures occur, respectively, in the region of 0.81 < x/l < 0.98, in the horizontal faces, and in the region of 0.93 < y/h < 0.98, in the vertical faces.