Mohammad‐Reza Alam
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View article: Submerged wave energy converter for deep water operations
Submerged wave energy converter for deep water operations Open
A submergible wave energy converter and method for using the same are described. Such a wave energy converter may be used for deep water operations. In one embodiment, the wave energy converter apparatus comprises an absorber having a body…
View article: Deep water wave cloaking using a multi-layered buoyant plate
Deep water wave cloaking using a multi-layered buoyant plate Open
Trajectory of surface gravity waves in potential flow regime is affected by the gravitational acceleration, water density, and seabed depth. While the gravitational acceleration and water density are approximately constant, the effect of w…
View article: Frequency-dependent higher-order Stokes singularities near a planar elastic boundary: Implications for the hydrodynamics of an active microswimmer near an elastic interface
Frequency-dependent higher-order Stokes singularities near a planar elastic boundary: Implications for the hydrodynamics of an active microswimmer near an elastic interface Open
The emerging field of self-driven active particles in fluid environments has recently created significant interest in the biophysics and bioengineering communities owing to their promising future for biomedical and technological applicatio…
View article: The Experimental Realization of an Artificial Low-Reynolds-Number Swimmer with Three-Dimensional Maneuverability
The Experimental Realization of an Artificial Low-Reynolds-Number Swimmer with Three-Dimensional Maneuverability Open
The motion of biological micro-robots -- similar to that of swimming microorganisms such as bacteria or spermatozoa -- is governed by different physical rules than what we experience in our daily life. This is particularly due to the low-R…
View article: The Experimental Realization of an Artificial Low-Reynolds-Number\n Swimmer with Three-Dimensional Maneuverability
The Experimental Realization of an Artificial Low-Reynolds-Number\n Swimmer with Three-Dimensional Maneuverability Open
The motion of biological micro-robots -- similar to that of swimming\nmicroorganisms such as bacteria or spermatozoa -- is governed by different\nphysical rules than what we experience in our daily life. This is particularly\ndue to the lo…
View article: In situ 3D reconfigurable ultrasonically sculpted optical beam paths
In situ 3D reconfigurable ultrasonically sculpted optical beam paths Open
We demonstrate that optical beams can be spatially and temporally shaped in situ by forming 3D reconfigurable interference patterns of ultrasound waves in the medium. In this technique, ultrasonic pressure waves induce a modulated refracti…
View article: Propulsion and Mixing Generated by the Digitized Gait of<i>Caenorhabditis elegans</i>
Propulsion and Mixing Generated by the Digitized Gait of<i>Caenorhabditis elegans</i> Open
Nematodes have evolved to swim in highly viscous environments. Artificial mechanisms that mimic the locomotory functions of nematodes can be efficient viscous pumps. We experimentally simulate the motion of the head segment of Caenorhabdit…
View article: Broadband Wall-less Waveguide for Shallow Water Waves
Broadband Wall-less Waveguide for Shallow Water Waves Open
We present a broadband waveguide for water waves obtained through mere manipulation of seabed properties and without any need for sidewalls. Specifically, we show that a viscoelastic seabed results in a modified effective gravity term in t…
View article: Flow characteristics of <i>Chlamydomonas</i> result in purely hydrodynamic scattering
Flow characteristics of <i>Chlamydomonas</i> result in purely hydrodynamic scattering Open
It has long been believed that eukaryotic flagellated swimming cells feel solid boundaries through direct ciliary contact. Specifically, based on observations of behavior of green alga Chlamydomonas reinhardtii it has been reported that it…
View article: Shape Optimization of Wave Energy Converters for Broadband Directional\n Incident Waves
Shape Optimization of Wave Energy Converters for Broadband Directional\n Incident Waves Open
Here, through a systematic methodology and the use of high performance\ncomputing, we calculate the optimum shape for a wave energy converter under the\naction of incident waves of (i) monochromatic unidirectional, (ii)\nmonochromatic dire…
View article: Rogue Wave Morphology in Broadband Nonbreaking Seas
Rogue Wave Morphology in Broadband Nonbreaking Seas Open
Here, we show through a statistical analysis that rogue waves in broadband non-breaking seas are spatially asymmetric. In addition to the top-down asymmetry due to nonlinear effects, we show that the two troughs adjacent to the rogue wave …
View article: Dominant Subharmonic Waves from Parametric Subharmonic Instability of Internal Waves
Dominant Subharmonic Waves from Parametric Subharmonic Instability of Internal Waves Open
Parametric Subharmonic Instability (PSI) is one of the most important mechanisms that transfer energy from tidally-generated long internal waves to short steep waves. Breaking of these short waves results in diapycnal mixing through which …
View article: Dominant Resonance in Parametric Subharmonic Instability of Internal Waves
Dominant Resonance in Parametric Subharmonic Instability of Internal Waves Open
Parametric Subharmonic Instability (PSI) is one of the most important mechanisms that transfer energy from tidally-generated long internal waves to short steep waves. Breaking of these short waves results in diapycnal mixing through which …
View article: Broadband cloaking of flexural waves
Broadband cloaking of flexural waves Open
The governing equation for elastic waves in flexural plates is not form invariant, and hence designing a cloak for such waves faces a major challenge. Here, we present the design of a perfect broadband cloak for flexural waves through the …
View article: Suppression of epileptic seizures via Anderson localization
Suppression of epileptic seizures via Anderson localization Open
Here we show that brain seizures can be effectively suppressed through random modulation of the brain medium. We use an established mesoscale cortical model in the form of a system of coupled stochastic partial differential equations. We s…
View article: Excitation of the Earth's Chandler wobble by a turbulent oceanic double-gyre
Excitation of the Earth's Chandler wobble by a turbulent oceanic double-gyre Open
We develop a layer-averaged, multiple-scale spectral ocean model and show how an oceanic double-gyre can communicate with the Earth's Chandler wobble. The overall transfers of energy and angular momentum from the double-gyre to the Chandle…
View article: Inherently unstable internal gravity waves due to resonant harmonic generation
Inherently unstable internal gravity waves due to resonant harmonic generation Open
Here we show that there exist internal gravity waves that are inherently unstable, that is, they cannot exist in nature for a long time. The instability mechanism is a one-way (irreversible) harmonic-generation resonance that permanently t…
View article: Oblique chain resonance of internal waves by three-dimensional seabed corrugations
Oblique chain resonance of internal waves by three-dimensional seabed corrugations Open
Here we show that the interaction of a low-mode internal wave with small oblique seabed corrugations can lead to a chain resonance of many other freely propagating internal waves with a broad range of wavenumbers and directions of propagat…
View article: Inherently Unstable Internal Gravity Waves
Inherently Unstable Internal Gravity Waves Open
Here we show that there exist internal gravity waves that are inherently unstable, that is, they cannot exist in nature for a long time. The instability mechanism is a one-way (irreversible) harmonic-generation resonance that permanently t…