Research The research activities of the faculty and students of Mechanical Engineering at Caltech span diverse areas involving thermal sciences, fluid and solid mechanics, and mechanical systems. The research is highly interdisciplinary and often conducted in a collaborative atmosphere. Despite our small size compared to our peer institutions, the Institute for Scientific Information ranks us number four worldwide for the strength of our research impact as measured by the number of citations of our papers. Our research is supported from diverse sources: the sponsored research expenditure of ME faculty at Caltech exceeded $ 10 Million in fiscal year 2007. Caltech ME has embarked on an Energy Engineering Initiative to address
urgent research concerning effective means to power the planet. Our
growing activities address fundamental issues that represent road-blocks
in technologies that have a major impact on energy.
A few examples of specific ongoing research projects are given below.
Nanoscale Architectural Engineering
Nanoscale Architectural Engineering for High Performance Solid Oxide Fuel Cells Solid oxide fuel cells (SOFCs), are the most efficient devices known to convert chemical energy stored in a fuel to electrical energy. In large-scale systems for stationary power generation with downstream heat recovery, efficiencies as high as 75% are projected, far in excess of what is possible with combustion systems. However, SOFCS have yet to see widespread use due to high costs and limited performance to date. To address these current research at Caltech ME uses advanced nano- and micro-structured materials, such as nanowires and inverse opal structures, along with chemical reaction models to develop high performance SOFCS
Explosions and Safety Accidental explosions, both flames and detonations, are serious potential hazards in the petrochemical, nuclear, power generation and transmission industries that use liquid and gaseous fuels. Analyzing, mitigating, and preventing explosions involves fundamental studies in combustion, fluid mechanics, solid mechanics, and fluid-structure interactions. Current research at Caltech ME addresses these issues through both experiment and simulation.
Multiscale Modeling of Materials
Multiscale modeling of materials "Crystals are like people: it is the defects in them that make them interesting", Sir F. Charles Franck. The reason for this is the complex physics of defects ranging the quantum mechanical physics at the nanometer scale to elastic interactions at the micrometer scale and beyond. Caltech ME researchers have recently developed a seamless method that bridges these scales by enabling electronic structure calculations at macroscopic scales. They are applying this method to diverse problems including the nucleation of prismatic dislocations, a key mechanism of irradiation damage in materials. Bhattacharya and Ortiz Groups
The Role of Forces During Cell Migration
The role of forces during cell migration Quantitative Characterization of 3D Deformations in Soft Biomaterials with applications to cell migration. This research uses a recently developed quantitative 3D imaging technique to measure full field displacements inside transparent soft biomaterials by combining laser scanning confocal microscopy and digital volume correlation. Currently, this method is used to study the deformation fields around migration fibroblast cells on synthetic gels and artificial extracellular matrix proteins.
Neural Prosthetics Many of us have probably had this fantasy: just by thinking, we direct our computer to turn on and open the document we want to work on. Or another perhaps: mentally commanding the cursor to move on the screen to a specific location. At Caltech, monkeys can already accomplish the latter. This feat has been achieved through groundbreaking interdisciplinary research that developed proof-of-concept neural prostheses and the associated technology that will someday allow use of these devices by humans. A neural prosthesis is a direct brain interface that enables a primate, via the use of surgically implanted electrode arrays and associated computer algorithms, to control external electromechanical devices by pure thought alone. The first beneficiaries of such technology are likely to be patients with spinal cord damage, peripheral nerve disease, or ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease). In the United States alone, there are 2.28 million cases of patients with some form of paralysis.
Simulation of the collapse of a spherical air bubble near a wall subjected to a shock wave. Numerical Schlieren (top) and pressure (bottom) contours illustrate the non-spherical deformation of the bubble and the generation of shockwaves during the collapse. The high pressure thereby produced during can lead to significant structural damage to neighboring structures. This phenomenon is exhibited in many applications, ranging from the erosion of propeller blades and pump impellers to the comminution of kidney stones.
Separated flow behind a rectangular airfoil Separated flows behind low-aspect-ratio wings have been of interest for the development of micro air vehicles as well as for understanding the flight mechanism of insect wings. Three-dimensional vortex formation and evolution around purely translating wings at low Reynolds numbers are investigated to understand how unsteady vortical forces can be used to increase lift. This study is a part of a larger research effort (MURI) to assist future design, control, and reduced order modeling of bio-inspired micro-air-vehicles.
Booming Sands Booming sand dunes have intrigued travelers since Marco Polo and puzzled scientists for long. Some dunes emit a persistent, low-frequency sound during a slumping event or a natural avalanche on the leeward face of the dune. The sound can last for several minutes and is audible from miles away. The resulting acoustic emission is characterized by a dominant audible frequency (70 - 105 Hz) and several higher harmonics. Seismic refraction experiments by Caltech ME proved the existence of a multi-layer internal structure in the dune that acts as a waveguide for the acoustic energy. Constructive interference between the reflecting waves enables the amplification and sets the frequency of each boom. Continuing work focuses on additional geophysical measurements and finite difference simulations supporting the waveguide model for booming sand dunes.
Active materials and devices Active materials display unusual coupling between mechanical, electric, magnetic, thermal and other properties. They are the basis for a number of technological applications since that one property can be controlled using another. Current research in Caltech ME ranges from fundamental understanding to specific applications. An example of the former is the development of new low-hysteresis active materials, and that of the latter is Ferroelectric Nanophotonic Devices that combine the geometric opportunities to localize light in photonic crystals with the inherent material complexities of ferroelectric materials to obtain unprecedented tunable photonic devices.
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