About

Silas Alben is a faculty member in the Department of Mathematics at the University of Michigan, with a focus on applied mathematics and continuum mechanics. His research addresses problems from biology, particularly biomechanics, and engineering, utilizing modeling, theoretical analysis, and the development of numerical methods to gain new physical insights into these problems. He holds a B.A. from Harvard University, an M.S. and Ph.D.. from New York University, obtained in 2002 and 2004 respectively. His work involves applying mathematical tools to understand biological and engineering phenomena, especially in the context of biomechanics.

Research topics

• Thermodynamics
• Physics
• Mechanics
• Classical mechanics
• Acoustics

Selected publications

• Comparison of inviscid and viscous vortex shedding from translating and rotating plates

  Open MIND · 2026-02-06

  preprintSenior author

  We compare an inviscid vortex sheet model with continuous leading-edge shedding with direct Navier-Stokes simulations over a wide range of unsteady plate motions at moderate Reynolds number ($\mathrm{Re} \approx 1000$). Approximately $70$ distinct kinematic configurations are examined, spanning both body-dominated and flow-dominated regimes. In body-dominated motions, where the fluid dynamics are primarily driven by prescribed plate accelerations, the inviscid model accurately reproduces normal force histories and the qualitative structure of the induced vorticity field. In flow-dominated configurations, with quasi-periodic vortex shedding, agreement with force predictions is good but reduced at low angles of attack, reflecting the greater sensitivity of vortex shedding dynamics to physical and computational parameters. The ability of the present formulation to accommodate stable, continuous leading-edge vortex shedding enables uniform comparisons across diverse motions and clarifies the regimes in which inviscid vortex sheet models can be used reliably for force prediction and physical interpretation.

  DOI

• Comparison of inviscid and viscous vortex shedding from translating and rotating plates

  ArXiv.org · 2026-02-06

  articleOpen accessSenior author

  We compare an inviscid vortex sheet model with continuous leading-edge shedding with direct Navier-Stokes simulations over a wide range of unsteady plate motions at moderate Reynolds number ($\mathrm{Re} \approx 1000$). Approximately $70$ distinct kinematic configurations are examined, spanning both body-dominated and flow-dominated regimes. In body-dominated motions, where the fluid dynamics are primarily driven by prescribed plate accelerations, the inviscid model accurately reproduces normal force histories and the qualitative structure of the induced vorticity field. In flow-dominated configurations, with quasi-periodic vortex shedding, agreement with force predictions is good but reduced at low angles of attack, reflecting the greater sensitivity of vortex shedding dynamics to physical and computational parameters. The ability of the present formulation to accommodate stable, continuous leading-edge vortex shedding enables uniform comparisons across diverse motions and clarifies the regimes in which inviscid vortex sheet models can be used reliably for force prediction and physical interpretation.

  PublisherOA PDF

• How vortices enhance heat transfer from an oscillating plate

  Journal of Fluid Mechanics · 2025-06-24 · 1 citations

  preprintOpen accessSenior authorCorresponding

  Oscillations of a heated solid surface in an oncoming fluid flow can increase heat transfer from the solid to the fluid. Previous studies have investigated the resulting heat transfer enhancement for the case of a circular cylinder undergoing translational or rotational motions. Another common geometry, the flat plate, has not been studied as thoroughly. The flat plate sheds larger and stronger vortices that are sensitive to the plate’s direction of oscillation. To study the effect of these vortices on heat transfer enhancement, we conduct two-dimensional numerical simulations to compute the heat transfer from a flat plate with different orientations and oscillation directions in an oncoming flow with Reynolds number 100. We consider plates with fixed temperature and fixed heat flux, and find large heat transfer enhancement in both cases. We investigate the effects of the plate orientation angle and the plate oscillation direction, velocity, amplitude and frequency, and find that the plate oscillation velocity and direction have the strongest effects on global heat transfer. The other parameters mainly affect the local heat transfer distributions through shed vorticity distributions. We also discuss the input power needed for the oscillating-plate system and the resulting Pareto optimal cases.

  PublisherOA PDFDOI

• Enhancing wall-to-wall heat transport with unsteady flow perturbations

  ArXiv.org · 2025-07-16

  preprintOpen access1st authorCorresponding

  We determine unsteady flow perturbations that are optimal for enhancing the rate of heat transfer between hot and cold walls (i.e. the Nusselt number Nu), under the constraint of fixed flow power (Pe$^2$, where Pe is the Péclet number). The unsteady flows are perturbations of previously computed optimal steady flows and are given by eigenmodes of the Hessian matrix of Nu, the matrix of second derivatives with respect to amplitudes of flow mode coefficients. Positive eigenvalues of the Hessian correspond to increases in Nu by unsteady flows, and occur at Pe $\geq 10^{3.5}$ and within a band of flow periods $τ\sim$ Pe$^{-1}$. For $τ$Pe $\leq 10^{0.5}$, the optimal flows are chains of vortices that move along the walls or along eddies enclosed by flow branches near the walls. At larger $τ$Pe the vorticity distributions are often more complex and extend farther from the walls. The heat flux is enhanced at locations on the walls near the unsteady vorticity. We construct an iterative time-spectral solver for the unsteady temperature field and find increases in Nu of up to 7% at moderate-to-large perturbation amplitudes.

  PublisherOA PDFDOI

• Sail dynamics during tacking maneuvers

  Physical Review Fluids · 2025-05-30 · 2 citations

  articleSenior author
  PublisherDOI

• Falling plates with leading-edge vortex shedding

  Physical Review Fluids · 2025-09-30

  articleOpen accessSenior author

  We present a numerical method for thin plates falling in inviscid fluid that incorporates leading-edge vortex shedding. Including leading-edge vortex shedding restores physical dynamics to inviscid vortex sheet simulations, enabling large-amplitude fluttering and tumbling.

  PublisherOA PDFDOI

• Enhancing wall-to-wall heat transport with unsteady flow perturbations

  Journal of Fluid Mechanics · 2025-12-09

  articleOpen access1st authorCorresponding

  We determine unsteady time-periodic flow perturbations that are optimal for enhancing the time-averaged rate of heat transfer between hot and cold walls (i.e. the Nusselt number Nu ), under the constraint of fixed flow power ( Pe $^2$ , where Pe is the Péclet number). The unsteady flows are perturbations of previously computed optimal steady flows and are given by eigenmodes of the Hessian matrix of Nu , the matrix of second derivatives with respect to amplitudes of flow mode coefficients. Positive eigenvalues of the Hessian correspond to increases in Nu by unsteady flows, and occur at $Pe\geqslant 10^{3.5}$ and within a band of flow periods $\tau \sim Pe^{-1}$ . For $\tau {\textit{Pe}}\leqslant 10^{0.5}$ , the optimal flows are chains of vortices that move along the walls or along eddies enclosed by flow branches near the walls. At larger $\tau {\textit{Pe}}$ , the vorticity distributions are often more complex and extend farther from the walls. The heat flux is enhanced at locations on the walls near the unsteady vorticity. We construct an iterative time-spectral solver for the unsteady temperature field, and find increases in Nu of up to 7 % at moderate-to-large perturbation amplitudes.

  PublisherDOI

• Spanwise variations in membrane flutter dynamics

  Journal of Fluids and Structures · 2024-10-14 · 2 citations

  articleSenior author
  PublisherDOI

• Enhancing heat transfer in a channel with unsteady flow perturbations

  arXiv (Cornell University) · 2024-09-23

  preprintOpen access1st authorCorresponding

  We compute unsteady perturbations that optimally increase the heat transfer (Nu) of optimal steady unidirectional channel flows, for a given average rate of power consumption Pe$^2$. The perturbations are expanded in a basis of modes, and the heat transfer enhancement corresponds to eigenvalues of the Hessian matrix of second derivatives of the Nusselt number with respect to the mode coefficients. Enhanced heat transfer, i.e. positive eigenvalues, occur in a range of temporal periods $τ$ that scale as Pe$^{-1}$. At small to moderate $τ$Pe values the corresponding flows are chains of eddies near the walls that move as traveling waves at the steady background flow speed. At large $τ$Pe the flows have eddies of multiple scales ranging up to the domain size. We use an unsteady solver to simulate these flows with perturbation sizes ranging from small to large, and find increases in Nu of up to 56% at Pe = 2$^{19}$. Large Nu can be obtained by eddies with small spatial/temporal scales and by eddies with a range of spatial scales and large temporal scales.

  PublisherOA PDFDOI

• Enhancing heat transfer in a channel with unsteady flow perturbations

  Physical Review Fluids · 2024-12-27 · 2 citations

  article1st authorCorresponding

  Recent studies have used optimization to determine fluid flows that can efficiently cool heated objects. This paper examines recently discovered steady optimal flows through a heated channel, and uses a perturbation method to find nearby unsteady flows that convect more heat - up to 80% - for a given amount of power needed to move the flow. The unsteady perturbations consist of vortices, small or large, that move along the channel walls and disrupt the thermal boundary layer.

  PublisherDOI

Recent grants

• PostDoctoral Research Fellowship

  NSF · $108k · 2004–2008

• Optimal Flows for Thermal Transport

  NSF · $231k · 2022–2026

• Collaborative Research: New models and numerical methods for flexible wings, fins, and membranes

  NSF · $131k · 2013–2015

• The optimization and control of flexible propulsors in inviscid fluids

  NSF · $152k · 2008–2012

• Computations and Analysis of Efficient Snake Locomotion

  NSF · $220k · 2018–2022

Frequent coauthors

• L. A. Miller

  Georgia Institute of Technology

  29 shared

• Jeannette Yen

  Georgia Institute of Technology

  27 shared

• Tyson L. Hedrick

  University of North Carolina at Chapel Hill

  26 shared

• Daniel I. Goldman

  26 shared

• Eric Tytell

  Tufts University

  26 shared

• Z. J. Wang

  State Street (United States)

  25 shared

• Michael Shelley

  20 shared

• George Lauder

  Harvard University

  18 shared