• Stratification and hydrodynamics of a hot water tank during charging are studied. • A 3D-CFD model was used to supplement previous experimental analyses. • A high degree of correlation with experiments and versatility was achieved. • New inlet configurations and two inflow rates were simulated and compared. • The role of some inlet characteristics on stratification is clarified.

This paper presents large eddy simulation of turbulent flow in a meandering open channel with smooth wall and rectangular cross-section. The Reynolds number based on the channel height is 40,000 and the aspect ratio of the cross-section is 4.48. The depth-averaged mean stream-wise velocity agree well to experimental measurements. In this specific case, two interacting cells are formed that swap from one bend to the other. Transport and mixing of a pollutant is analysed using three different positions of release, e.g. on the inner bank, on the outer bank and on the centre of the cross section. The obtained depth-average mean concentration profiles are reasonably consistent with available experimental data. The role of the secondary motions in the mixing processes is the main focus of the discussion. It is found that the mixing when the scalar is released on the centre of the cross-section is stronger and faster than the mixing of the scalar released on the sides. When the position of release is close to a bank side, the mixing is weaker and a clear concentration of scalar close to the corresponding side-wall can be observed in both cases. Acknowledgements: The simulation was carried out using the supercomputing facilities of the Steinbuch Centre for Computing (SCC) of the Karlsruhe Institute of Technology. The authors would like to thank Clemens Chan-Braun for his valuable and constructive suggestions during the development of this research. MGV acknowledges the financial support of the Spanish Ministry of Education through the program Jose Castillejo.

ElsevierGasque Albalate, M.; González Altozano, P.; Maurer, D.; Moncho Esteve, IJ.; Gutiérrez-Colomer, RP.; Palau-Salvador, G.; García-Mari, E. (2015). Study of the influence of inner lining material on thermal stratification in a hot water storage tank. Applied Thermal Engineering. 75:344-356. doi:10.1016Engineering. 75:344-356. doi:10. /j.applthermaleng.2014 ABSTRACTThe present study has analyzed the influence of thermal conductivity of the inner lining material on the stratification process in a hot water tank during thermal charge and the later standby period. This analysis has been carried out numerically by a three-dimensional Computational Fluid Dynamics (CFD) model. Experimental measurements of temperature profiles are used to select and verificate the model, and to later validate CFD simulations. With the validated model, temperature over time at several heights, temperature profiles, velocity contours, water streamtraces and temperature contours, are studied and compared for three different inner lining materials. The obtained results confirm that a weak conducting lining material favours energy storage in the tank and the thermal stratification of water during charge and subsequent standby period. The effect of the inner lining material on the energy accumulated in water and on the moment of energy (stratification) is potentially enhanced when the material's thermal conductivity diminishes. The use of insulating paints as inner lining for water storage tanks could be a possible solution to be studied and subsequently adopted in practice to improve the efficient use of energy in stored water. The analysis 2 techniques employed prove most useful and enable the results to be compared and presented in a novel way.

In this study, we report large eddy simulations of turbulent flow in a periodic compound meandering channel for three different depth conditions: one in-bank and two overbank conditions. The flow configuration corresponds to the experiments of Shiono and Muto (1998). The predicted mean streamwise velocities, mean secondary motions, velocity fluctuations, turbulent kinetic energy as well as mean flood flow angle to meandering channel are in good agreement with the experimental measurements. We have analyzed the flow structure as a function of the inundation level, with particular emphasis on the development of the secondary motions due to the interaction between the main channel and the floodplain flow. Bed shear stresses have been also estimated in the simulations. Floodplain flow has a significant impact on the flow structure leading to significantly different bed shear stress patterns within the main meandering channel. The implications of these results for natural compound meandering channels are also discussed.

Moncho Esteve, IJ.; Palau-Salvador, G.; Brevis, W.; Vaas, M.; López Jiménez, PA. (2015). Numerical simulation of the hydrodynamics and turbulent mixing process in a drinking water storage tank. Journal of Hydraulic Research. 52 (2)