Dissertation
I. RADIATION FORCES AND TORQUES OF ACOUSTIC BEAMS; II. CAPILLARY WAVES IN PERIODICALLY SUPPORTED CHANNELS
Doctor of Philosophy (PhD), Washington State University
01/2012
Handle:
https://hdl.handle.net/2376/118468
Abstract
Acoustic beams, analogous to optical beams, can transfer linear momentum and/or angular momentum to illuminated objects, and hence exert radiation forces and/or torques on the objects. Part I of this dissertation analyzes negative radiation forces by non-diffracting beams, angular momentum transport of vortex beams, and associated radiation torques on objects. Experimental realization will allow innovative applications especially for the manipulation of microparticles by traveling waves. Main results are as follows. The negative force is interpreted in terms of momentum conservation and scattering asymmetry. Analysis beyond the paraxial approximation indicates that the ratio of the axial (or radial) flux density of axial angular momentum to the axial (or radial) flux density of energy equals to the ratio of the vortex beam's topological charge to the acoustic frequency, and the axial radiation torque on an axisymmetric object centered on the beam's axis is proportional to the power absorbed by the object. The extinction / scattered / absorbed powers and scattering asymmetry associated with a non-diffracting Bessel beam are related to the beam's conic angle and the scattering partial wave coefficients.
Part II concerns fluid containment and control for life support technologies for long-duration manned space missions. Surface tension allows the utilization of minimal surface-intersecting support structures to stabilize a meniscus. Capillary waves occurring at surfaces tend to be important. For example, a stable liquid cylinder can be supported in zero gravity by a helical spring that constrains the free surface against instability. This capillary channel geometry is proposed for phase separation because of its ability to capture impacting droplets. Drops that impact the channel are seen to launch capillary waves emanating from the impact point that travel along the channel and disperse energy. Some aspects of capillary wave dynamics in open capillary channels are investigated in this dissertation including: the interaction of capillary waves with surface-intersecting structures, the effect of dynamic contact lines on wave dissipation, capillary bridge resonances and their connection with capillary wave scattering, and modeling of capillary wave propagation along periodically supported liquid cylinders to predict dispersion and wave speed.
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Details
- Title
- I. RADIATION FORCES AND TORQUES OF ACOUSTIC BEAMS; II. CAPILLARY WAVES IN PERIODICALLY SUPPORTED CHANNELS
- Creators
- Likun Zhang
- Contributors
- Philip L Marston (Advisor)Philip L Marston (Committee Member)David B Thiessen (Committee Member)Valipuram S Manoranjan (Committee Member)Chuanwei Zhang (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Physics and Astronomy, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 151
- Identifiers
- 99900581748401842
- Language
- English
- Resource Type
- Dissertation