Experimental ivnestigation on flow fields of viscous fluid around two-dimensional wings and comparison with computational results

To examine the flow field of a viscous fluid around the trailing edge of a wing with respect to the Kutta condition or the Joukowski hypothesis, an experimental investigation into the velocity fields around two-dimensional (2D) wings NACA0012 and NACA4412 was carried out using an X-type hot-wire anemometer in a wind tunnel and the method of colored milk injection in a circulating water channel. The results of these investigations revealed that the flow of a viscous fluid at the trailing edge of a 2D wing is tangential to the face on the pressure side, and that the flow is very slow or reversed on the suction side due to separation when the angle of attack is greater than 7.5°. By flow visualization, a Kármán vortex street was found in the wake of both wings (NACA0012 and NACA4412) when the angle of attack was 5°. These results show that the ordinary Kutta condition with respect to the direction of outflow at the trailing edge is not necessarily satisfied in a viscous fluid, but the Kutta condition with respect to the pressure at the trailing edge is satisfied as usual. Numerical results, which have been obtained as the solution of Reynolds-averaged Navier-Stokes equations, show good agreement with above-mentioned experimental results. Therefore, CFD (Computational Fluid Dynamics) simulation has proved to be very effective for studying steady viscous flow around the trailing edge of a 2D wing.     

Experimental Study of Effects of Travel Time Distribution Information on Dynamic Route Choice Behavior

This study focuses on the possibility that providing travelers with information on travel time distribution, along with the existing travel time information, might affect their decision making and enhance traffic control. As an initial step to confirm the effectiveness of travel time distribution information, we use a laboratory experiment to obtain panel data of route choices when information is provided. The rationality of the behavior of the respondents and the characteristics of the route choice are first analyzed by aggregation analysis and then statistically examined by specifying a mixed logit route choice model. As a result, it is revealed that both travel time information and maximum travel time information significantly affect route choice behavior when a penalty is imposed for late arrival.     

Numerical Calculation of Marine Propeller Hydrodynamic Characteristics in Unsteady Flow by Boundary Element Method

In this paper, a low-order potential based on surface panel method is used for the analysis of marine propellers in unsteady flow.A linear propeller wake model is employed and its geometry is assumed to be independent of the time.The calculation in time domain is carried out from a moment when the rotation of the propeller becomes steady instead of from the moment when the rotation strats from stationary condition.At every time step a linear algebraic equation established on a key blade is solved numerically combined with the Kutta pressure conditon.The calculated results by developed code indicate good convergency and effrctiveness of present algotithm for conventional propellers and highly skewed propellers.