Motion of sediment particles in a Rankine combined vortex

CER84-85PYJ6.Includes bibliographical references (page 28).May 1985

Planform geometry of meandering alluvial channels

CER84-85PYJ5.Includes bibliographical references (pages 32-49).May 1985

Laboratory notes on stratification of sands

CER93-94-PYJ-YR-1.Includes bibliographical references (pages 76-77).November 1993

Laboratory experiments on lamination, stratification and desiccation

CER89-90-PYL-YQL-15.Includes bibliographical references (pages 158-162).May 1990. Revised July 1990.Funded by M. Guy Berthault

BUFFER LAW AND TRANSITIONAL ROUGHNESS EFFECT IN TURBULENT OPEN-CHANNEL FLOWS

A novel and complete velocity profile law is presented for turbulent open channel flows. The law embeds the linear law in the viscous sublayer; the quartic law due to turbulent bursting that must satisfy instantaneous mass conservation, the modified log-wake law in the outer region and the effects of wall roughness. Specifically, an arctangent law smoothly connects the linear law with the log law of the wall. Combining the arctangent law with the modified log-wake law, a continuous velocity profile is proposed for smooth boundary conditions. A complete velocity profile is obtained after subtracting a new roughness function. Finally, the proposed laws have been validated with data for hydraulically smooth, transitional and rough turbulent regimes

CASC2D user's manual: a two-dimensional watershed rainfall-runoff model

CER90-91PYJ-BS-12.Includes bibliographical references (page 50).March 1991.Funded by the U.S. Army Research Office Grant No. ARO/DAAL03-86-K-0175

Resistance to sheet flow

CER88-89BS-PYJ13.Includes bibliographical references (pages 58-62).January 1989.The results of a literature review on resistance to sheet flow are presented. The effects of surface roughness, rainfall, and vegetation are considered. At least in the case of laminar flow, it is found that the total flow resistance is the sum of the contributions of individual effects. The friction factor for the surface roughness effect in laminar flow is directly proportional to the relative roughness and varies inversely with the Reynolds number. A power function of rainfall intensity in laminar flow can represent the effect of rainfall on the product of friction factor and Reynolds number. For turbulent flow, however, the friction factor depends on the surface conditions which are partitioned into smooth, transition, and fully rough. The analysis of flow through vegetation is more complex and calls for further studies. For densely vegetated surfaces, the Darcy-Weisbach friction factor is shown to decrease significantly at Reynolds number well beyond the critical value of Re = 2000 for smooth surfaces. In some cases, the flow behaved as laminar flow at Re = 100,000.Funded by the U.S. Army Research Office Grant No. ARO/DAAL 03-86-K-0175

Formation of roll waves in laminar street flow

CER84-85PYJ-DMH18.Includes bibliographical references (pages 24-25).January 1985

KINSC user's manual: kinematic wave models for flood routing in a stream channel

CER88-89AM-GWC-PYJ12.Includes bibliographical references (pages 35-36).March 1989.U.S. Army Research Office (Grant No. ARO/DAAL 03-86-K-0175)

Conceptual study for a sub-pupil instrument having 4 high order adaptive optics paths for parallel multi-wavelength high contrast imaging, and medium resolution spectrometry

We present the concept of an instrument that will create 4 circular sub-pupils of 3 m in diameter. Each sub-pupil path will be corrected by a high order adaptive optics system (SR~80% in H) without spider and M2 obstruction. These four independent channels, obviously all pointed towards the same field, allows the possibility of covering totally different parts of the electromagnetic spectrum simultaneously without compromising Signal to Noise Ratio. Each channel can be dedicated to very specialized but complementary purposes: high contrast imaging, pseudo-wide field imaging, high precision multi-color photometry, medium-resolution spectroscopy, polarimetry and sparse-aperture masking