Linear stability of ultrathin slipping films with insoluble surfactant

2005 ◽  
Vol 17 (8) ◽  
pp. 088105 ◽  
Author(s):  
Guo-Hui Hu
Keyword(s):  
Linear Stability ◽  
Insoluble Surfactant

Stability of surfactant-laden core–annular flow and rod–annular flow to non-axisymmetric modes

2013 ◽  
Vol 716 ◽  
Author(s):  
M. G. Blyth ◽  
Andrew P. Bassom
Keyword(s):  
Linear Stability ◽  
Annular Flow ◽  
Convective Motion ◽  
Straight Pipe ◽  
Pipe Axis ◽  
Insoluble Surfactant ◽  
Fluid Layers ◽  
Axisymmetric Disturbances ◽  
Quiescent Fluid ◽  
Fluid Configuration

AbstractThe linear stability of core–annular fluid arrangements are considered in which two concentric viscous fluid layers occupy the annular region within a straight pipe with a solid rod mounted on its axis when the interface between the fluids is coated with an insoluble surfactant. The linear stability of this arrangement is studied in two scenarios: one for core–annular flow in the absence of the rod and the second for rod–annular flow when the rod moves parallel to itself along the pipe axis at a prescribed velocity. In the latter case the effect of convective motion on a quiescent fluid configuration is also considered. For both flows the emphasis is placed on non-axisymmetric modes; in particular their impact on the recent stabilization to axisymmetric modes at zero Reynolds number discovered by Bassom, Blyth and Papageorgiou (J. Fluid. Mech., vol. 704, 2012, pp. 333–359) is assessed. It is found that in general non-axisymmetric disturbances do not undermine this stabilization, but under certain conditions the flow may be linearly stable to axisymmetric disturbances but linearly unstable to non-axisymmetric disturbances.

scholarly journals Instabilities at a sheared interface over a liquid laden with soluble surfactant

2021 ◽  
Vol 129 (1) ◽  
Author(s):  
A. Kalogirou ◽  
M. G. Blyth
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Fluid Layer ◽  
Threshold Value ◽  
Long Wavelength ◽  
Budget Analysis ◽  
Insoluble Surfactant ◽  
Bounded Below ◽  
Soluble Surfactant

AbstractThe linear stability of a semi-infinite fluid undergoing a shearing motion over a fluid layer that is laden with soluble surfactant and that is bounded below by a plane wall is investigated under conditions of Stokes flow. While it is known that this configuration is unstable in the presence of an insoluble surfactant, it is shown via a linear stability analysis that surfactant solubility has a stabilising effect on the flow. As the solubility increases, large-wavelength perturbations are stabilised first, leaving open the possibility of mid-wave instability for moderate surfactant solubilities, and the flow is fully stabilised when the solubility exceeds a threshold value. The predictions of the linear stability analysis are supported by an energy budget analysis which is also used to determine the key physical effects responsible for the (de)stabilisation. Asymptotic expansions performed for long-wavelength perturbations turn out to be non-uniform in the insoluble surfactant limit. In keeping with the findings for insoluble surfactant obtained by Pozrikidis & Hill (IMA J Appl Math 76:859–875, 2011), the presence of the wall is found to be a crucial factor in the instability.

Binding of Tissue Plasminogen Activator to Vascular Grafts

1989 ◽  
Vol 61 (01) ◽  
pp. 131-136 ◽  
Author(s):  
Richard A Harvey ◽  
Hugh C Kim ◽  
Jonathan Pincus ◽  
Stanley Z Trooskin ◽  
Josiah N Wilcox ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Fibrinolytic Activity ◽  
Polymer Surface ◽  
Enzymic Activity ◽  
Vascular Prostheses ◽  
Chemically Modified ◽  
Insoluble Surfactant ◽  
Tissue Plasminogen

SummaryTissue plasminogen activator labeled with radioactive iodine (125I-tPA) was immobilized on vascular prostheses chemically modified with a thin coating of water-insoluble surfactant, tridodecylmethylammonium chloride (TDM AC). Surfactant- treated Dacron, polytetrafluoroethylene (PTFE), silastic, polyethylene and polyurethane bound appreciable amounts of 125I- tPA (5-30 μg 125I-tPA/cm2). Upon exposure to human plasma, the amount of 125I-tPA bound to the surface shows an initial drop during the first hour of incubation, followed by a slower, roughly exponential release with a t½ of appoximately 75 hours. Prostheses containing bound tPA show fibrinolytic activity as measured both by lysis of clots formed in vitro, and by hydrolysis of a synthetic polypeptide substrate. Prior to incubation in plasma, tPA bound to a polymer surface has an enzymic activity similar, if not identical to that of the native enzyme in buffered solution. However, exposure to plasma causes a decrease in the fibrinolytic activity of both bound tPA and enzyme released from the surface of the polymer. These data demonstrate that surfactant-treated prostheses can bind tPA, and that these chemically modified devices can act as a slow-release drug delivery system with the potential for reducing prosthesis-induced thromboembolism.

Linear stability of hypersonic flow in thermochemical nonequilibrium

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 958-964
Author(s):  
Mary L. Hudson ◽  
Ndaona Chokani ◽  
Graham V. Candler
Keyword(s):  
Hypersonic Flow ◽  
Linear Stability
Sign in / Sign up

Export Citation Format

Share Document