Effect of crossflow on Goertler instability in incompressible boundary layers

Linear stability theory is used to study the effect of crossflow on Goertler instability in incompressible boundary layers. The results cover a wide range of sweep angle, pressure gradient, and wall curvature parameters. It is shown that the crossflow stabilizes Goertler disturbances by reducing the maximum growth rate and shrinking the unstable band of spanwise wave numbers. On the other hand, the effect of concave wall curvature on crossflow instability is destabilizing. Calculations show that the changeover from Goertler to crossflow instabilities is a function of Goertler number, pressure gradient, and sweep angle. The results demonstrate that Goertler instability may still be relevant in the transition process on swept wings even at large angles of sweep if the pressure gradient is sufficiently small. The influence of pressure gradient and sweep can be combined by defining a crossflow Reynolds number. Thus, the changeover from Goertler to crossflow instability takes place at some critical crossflow Reynolds number whose value increases with Goertler number

Bidding at Sequential First-Price Auctions with(out) Supply Uncertainty: A Laboratory Analysis

We report on a series of experiments that test the effects of an uncertain supply on the formation of bids and prices in sequential first-price auctions with private-independent values and unit-demands. Supply is assumed uncertain when buyers do not know the exact number of units to be sold (i.e., the length of the sequence). Although we observe a non-monotone behavior when supply is certain and an important overbidding, the data qualitatively support our price trend predictions and the risk neutral Nash equilibrium model of bidding for the last stage of a sequence, whether supply is certain or not. Our study shows that behavior in these markets changes significantly with the presence of an uncertain supply, and that it can be explained by assuming that bidders formulate pessimistic beliefs about the occurrence of another stage.Financial support from the University of Valencia (project GV98_08/2960) and from a EU-TMR ENDEAR Network Grant (FMRX-CT98-0238) is gratefully acknowledged

St. John's Daily Star, 1920-04-29

The St. John's Daily Star was published daily except Sunday between 17 April 1915 - 23 July 1921

Stratified thermal storage tank inlet mixing characterization

Predictions of thermocline development in thermocline thermal storage tanks can be made by accounting for turbulent mixing at the inlet region. A practical measure for quantifying this mixing is obtained by introducing an effective diffusivity factor in a one-dimensional flow model. Thus, a tool for characterization of turbulent mixing caused by different inlet configurations is now available. This should facilitate the selection of diffusers for achieving a high degree of stratification in thermocline thermal storage tanks.