Flow visualization using momentum and energy transport tubes and applications to turbulent flow in wind farms

As a generalization of the mass-flux based classical stream-tube, the concept of momentum and energy transport tubes is discussed as a flow visualization tool. These transport tubes have the property, respectively, that no fluxes of momentum or energy exist over their respective tube mantles. As an example application using data from large-eddy simulation, such tubes are visualized for the mean-flow structure of turbulent flow in large wind farms, in fully developed wind-turbine-array boundary layers. The three-dimensional organization of energy transport tubes changes considerably when turbine spacings are varied, enabling the visualization of the path taken by the kinetic energy flux that is ultimately available at any given turbine within the array.Comment: Accepted for publication in Journal of Fluid Mechanic

Direct Measurement of Vanadium Crossover in an Operating Vanadium Redox Flow Battery

Measurements of Vanadium diffusion coefficients for transport across cation exchange membranes using dialysis cells have been reported in the literature. However, to date direct measurement of crossover coefficients in an operating Vanadium redox flow battery (VRB) cell have not been reported. Results are reported in this paper on experiments utilizing a special VRB cell which allows measurement of Vanadium ion transport across ion exchange membranes with and without the presence of current. The cell utilizes two additional flow regions which collect Vanadium ions which diffuse from the positive and negative half cells. The effects of the magnitude and direction of electrical current on transport can be measured directly with this cell. We observe that transport is greatly enhanced when the direction of the hydrogen ion flux is in the same direction as the density gradient driven vanadium flux and suppressed when the hydrogen ion flux is in the opposite direction. The cell has been used to of investigate the effects on transport of current densities up to 900 mA/cm(2).US Department of Energy ARPA-E program DE-AR00000149Materials Science and Engineerin

The Colorado River Compact: A Limit on Upper Basin Development: Outline

9 pages. Contains references. Supplemental materials. Includes extracts from Colorado River Basin Project Act and Colorado River Compact

In Defense of Private Rights in Water

4 pages. Includes unsigned annotations by David Getches

The Colorado River Compact: A Limit on Upper Basin Development: Outline

9 pages. Contains references. Supplemental materials. Includes extracts from Colorado River Basin Project Act and Colorado River Compact