# Fluid Mechanics and Waves Seminar - Spring 2020

Seminars are held on Mondays from 2:30 - 3:30PM in Cullimore Hall, Room 611, unless noted otherwise.

Seminars are held on Mondays from 2:30 - 3:30PM in Cullimore Hall, Room 611, unless noted otherwise.

For questions about the seminar schedule, please contact Anand Oza.

To join the Fluid Mechanics and Waves seminar mailing list visit https://groups.google.com/a/njit.edu/forum/#!forum/math-fmws/join (Google Profile required). To join the mailing list without a Google Profile, submit the seminar request form.

Date | Speaker, Affiliation, Title, and Abstract | Host |
---|---|---|

February 10 |
A motion of fluid's free surface is considered in two dimensional (2D) geometry. A time-dependent conformal transformation maps a fluid domain into the lower complex half-plane of a new spatial variable. The fluid dynamics is fully characterized by the complex singularities in the upper complex half-plane of the conformal map and the complex velocity. Both a single ideal fluid dynamics (corresponds e.g. to oceanic waves dynamics) and a dynamics of superfluid Helium 4 with two fluid components are considered. Both systems share the same type of the non-canonical Hamiltonian structure. A superfluid Helium case is shown to be completely integrable for the zero gravity and surface tension limit with the exact reduction to the Laplace growth equation which is completely integrable through the connection to the dispersionless limit of the integrable Toda hierarchy and existence of the infinite set of complex pole solutions. A single fluid case with nonzero gravity and surface tension turns more complicated with the infinite set of new moving poles solutions found which are however unavoidably coupled with the emerging moving branch points in the upper half-plane. Residues of poles are the constants of motion. These constants commute with each other in the sense of underlying non-canonical Hamiltonian dynamics. It suggests that the existence of these extra constants of motion provides an argument in support of the conjecture of complete Hamiltonian integrability of 2D free surface hydrodynamics. |
Michael Siegel |

February 24 |
In the context of ocean-atmosphere interactions, many physical processes involve the generation of surface waves by turbulent background flows in air or in water. Although the dynamics of turbulent flows is only partly understood, I have recently shown that interfacial dynamics generated by turbulent flows can be quantitatively described in some cases. I will illustrate the pathway using two examples : the premices of surface waves generated by the wind, and the fragmentation of a single bubble in a turbulent background flow. I will eventually discuss how this approach could renew our understanding of wave dynamics at high Reynolds number. |
Anand Oza |

March 23 |
Many owl species rely on specialized plumage to mitigate their aerodynamic noise and achieve functionally-silent flight while hunting. One such plumage feature, a tattered arrangement of flexible trailing-edge feathers, is idealized as a semi-infinite poroelastic plate to model the effects that edge compliance and flow seepage have on the noise production. The interaction of the poroelastic edge with a turbulent eddy is examined analytically with respect to how efficiently the edge scatters the eddy as aerodynamic noise. The scattering problem is solved using the Wiener-Hopf technique to identify how the noise scales with the flight velocity, where special attention is paid to the limiting cases of rigid-porous and elastic-impermeable plate conditions. Results from this analysis identify new parameter spaces where the porous and/or elastic properties of a trailing edge may be tailored to diminish or effectively eliminate the edge scattering effect and may contribute to the owl hush-kit. |
Anand Oza |

April 6 |
Colloidal particles at fluid-fluid interfaces exhibit rich transport and interfacial phenomena. This multi-component, multi-phase system not only allows researchers to explore a variety of fundamental questions in colloid and interface science, but also plays important roles in many practical applications. For example, the use of the fluid-fluid interface as a two-dimensional template facilitates the assembly of colloidal monolayers with diverse nano/microstructures, which opens a new avenue for manufacturing thin film materials. However, these structures suspended at the fluidic interface must be transferred into a dried form for practical applications. Evaporative deposition is the most widely used approach to obtain dry materials, but this process can be complicated by the well-known coffee-ring effect. The interplay of particle adsorption/desorption, capillary interaction, and surface hydrodynamics and heat transfer needs to be uncovered to establish the critical processing-structure relationship and allow better use of this interfacial system. This presentation will discuss recent advances in computational modeling and experimentation for understanding the dynamics of colloids on the surface of evaporating liquid masses and how colloidal interfacial assembly modulates deposition structures. |
Yuan-nan Young |

April 20 |
Abstract: TBA |
David Shirokoff |

May 4 |
Abstract: TBA |
Anand Oza |

*Updated: January 28, 2020*