Periodic and Quasiperiodic Motion of an Elongated Microswimmer in Poiseuille Flow

We study the dynamics of a prolate spheroidal microswimmer in Poiseuille flow for different flow geometries. When moving between two parallel plates or in a cylindrical microchannel, the swimmer performs either periodic swinging or periodic tumbling motion. Although the trajectories of spherical and elongated swimmers are qualitatively similar, the swinging and tumbling frequency strongly depends on the aspect ratio of the swimmer. In channels with reduced symmetry the swimmers perform quasiperiodic motion which we demonstrate explicitely for swimming in a channel with elliptical cross section

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Measurement of the dynamic performance of the main drive fan of the RAE 5 metre pressurised low speed wind tunnel

SIGLELD:8717.806(RAE-TR--80043) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Some applications of Hartmann-type sources in aircraft noise research

SIGLELD:8670.2(RAE-TM-AERO--1877). / BLDSC - British Library Document Supply CentreGBUnited Kingdo

An Analysis Of Flow Behavior From A Gas Turbine Combustor Using A Laser Doppler Velcimeter

The purpose of this research was to analyze the flow behavior of air through a combustor and pilot assembly. The combustor was designed to support a combustion flame in gas turbine, and the pilot was the apparatus by which fuel would be supplied to the flame. This research was performed at the University of Central Florida main campus in Orlando, Fl., and was sponsored by Siemens-Westinghouse Power Corporation (SWPC). The combustor and pilot were supplied by SWPC for the purpose of characterizing the flow behavior through them. The focus of the research was to determine the axial and tangential velocity components of the flow. Both components were present due to the fact that the assembly was designed to produce a swirled flow, resulting in a recirculation zone. The main goal of the research conducted was to aid in the combustor design process of SWPC. Measurement of the velocity components was done by using a laser doppler velocimeter (LDV). This research was performed under the supervision of Dr. Ruey-Hung Chen of the Mechanical, Materials, and Aerospace Engineering (MMAE) Department of the University of Central Florida, and will be submitted in partial fulfillment for the Master\u27s Degree in Aerospace Engineering. © 2001 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved