Howard H. Hu

Computational Fluid Dynamics

Fluid Mechanics · 2012-01-01 · 129 citations

Equilibrium positions of the elasto-inertial particle migration in rectangular channel flow of Oldroyd-B viscoelastic fluids

Journal of Fluid Mechanics · 2019-04-11 · 62 citations

In this paper, the lateral migration of a neutrally buoyant spherical particle in the pressure-driven rectangular channel flow of an Oldroyd-B fluid is numerically investigated with a fictitious domain method. The aspect ratio of the channel cross-section considered is 1 and 2, respectively. The particle lateral motion trajectories are shown for the bulk Reynolds number ranging from 1 to 100, the ratio of the solvent viscosity to the total viscosity being 0.5, and a Weissenberg number up to 1.5.…

Shape Dynamics and Rheology of Soft Elastic Particles in a Shear Flow

Physical Review Letters · 2012-01-31 · 57 citations

The shape dynamics of soft, elastic particles in an unbounded simple shear flow is investigated theoretically under Stokes flow conditions. Three types of motion-steady-state, trembling, and tumbling-are predicted, depending on the shear rate, elastic shear modulus, and initial particle shape. The steady-state motion is found to be always stable. In addition, the existence of a trembling regime is documented for the first time in nonvesicle systems, and a complete phase diagram is developed. The…

Photophoretic Levitation of Macroscopic Nanocardboard Plates

Advanced Materials · 2020 · 31 citations

Scaling down miniature rotorcraft and flapping-wing flyers to sub-centimeter dimensions is challenging due to complex electronics requirements, manufacturing limitations, and the increase in viscous damping at low Reynolds numbers. Photophoresis, or light-driven fluid flow, was previously used to levitate solid particles without any moving parts, but only with sizes of 1-20 µm. Here, architected metamaterial plates with 50 nm thickness are leveraged to realize photophoretic levitation at the mil…

Controlled Levitation Of Nanostructured Thin Films For Sun-Powered Near-Space Flight

Science Advances · 2021 · 30 citations

Earth’s mesosphere is the least studied part of our atmosphere. The data it contains within itself can help develop more comprehensive and accurate models of the atmosphere and can help us understand our climate better. The main challenge before scientists is the inaccessibility of this region. The pressure is not high enough for aircraft and balloons and it is too high for satellites. There are remote sensing methods as well as transient rockets to collect data, though they are expensive and co…