QLS Seminar: Thursday, 5 July at 11h00

[Quantitative Life Sciences]

*QUANTITATIVE LIFE SCIENCES SEMINAR**
**
Thursday**, 5 July 2018 at 11:00,**
*ICTP, Central Area, 2nd floor, old SISSA building, via Beirut 2*
*

*Speaker*:  Mahesh M. Bandi, OIST, Okinawa, Japan & QLS Staff Associate

*Title*:  Hydrodynamic signatures of stationary Marangoni-driven 
surfactant transport

*Abstract*:
Surfactant spreading at air-water interfaces is driven by flow setup by 
surface tension gradients (Marangoni stress) established by the 
surfactants themselves. We experimentally probe the nature of steady 
surfactant transport on the interface when the resulting flow is 
strongest in a thin boundary layer near the interface. In particular, we 
present three experimental hydrodynamic signatures to distinguish 
between two limiting cases, viz. adsorption versus dissolution dominated 
transport, without invoking the surfactant's physico-chemical 
properties. In a region much larger than the surfactant source, but much 
smaller than the interfacial area, the steady-state fluid velocity 
assumes a self-similar form whose magnitude decays as a power-law with 
the distance from the source. We experimentally demonstrate that this 
power-law possesses an exponent -3/5 in adsorption and -1 in dissolution 
dominated flow. Explicit measurement of boundary layer and shear stress 
provide additional hydrodynamic signatures of surfactant transport 
mechanisms in the two limiting cases. We test this criterion against two 
known surfactants, Sodium Dodecyl Sulfate and Tergitol 15-S-9, and apply 
the results to camphoric acid, with unknown surface properties.

Indico web page: http://indico.ictp.it/event/8611/

Everyone interested is most welcome to attend!

-- 
Erica Sarnataro
Group Secretary
Quantitative Life Sciences
The Abdus Salam International Centre for Theoretical Physics (ICTP)
Trieste,  Italy
Tel. +39-040-2240623
www.ictp.it/research/qls.aspx
e-mail: qls at ictp.it