Interaction between a laminar starting immersed micro-jet and a parallel wall

Abstract

In the present work, we study the starting transient of an immersed micro-jet in close vicinity to a solid wall parallel to its axis. The experiments concern laminar jets (Re < 200) issuing from a 100 µm internal tip diameter glass micro-pipette. The effect of the confinement was studied placing the micro-pipette at different distances from the wall. The characterization of the jet was carried out by visualizations on which the morphology of the vortex head and trajectories was analyzed. Numerical simulations were used as a complementary tool for the analysis. The jet remains stable for very long distances away from the tip allowing for a similarity analysis. The self-similar behavior of the starting jet has been studied in terms of the frontline position with time. A symmetric and a wall dominated regime could be identified. The starting jet in the wall type regime, and in the symmetric regime as well, develops a self-similar behavior that has a relative rapid loss of memory of the preceding condition of the flow. Scaling for both regimes are those that correspond to viscous dominated flows.

Three-Dimensional Transport Model for Intravitreal and Suprachoroidal Drug Injection

“…For intravitreal injection of a solution containing certain substances, assuming the injected fluid is less viscous than the vitreous humor (the relative viscosity of vitreous humor has been reported as 1.59) 37 and the injection of approximately 50 μL liquid is performed using a 28-gauge (G) or similar needle within one second, the Reynolds number is estimated to be approximately 350. Based on an experimental study of a submerged fluid jet injected into a reservoir, with the same or different viscosities, 35 , 36 significant mixing would occur during the injection process. The viscosity of the human vitreous depends on many factors, such as age and disease.…”

“…Note that the hydrodynamics of mixing for fluids with different viscosities and specific gravities relevant to the problem of intravitreal injection is a complex phenomenon and has not been investigated to our knowledge; however, relevant studies for a fluid jet impinging on a fluid reservoir suggest that the mixing effect is significant. 35 , 36 The degree of the initial mixing that occurs following intravitreal injection is explored in more detail in the Results section. We also assume a similar initial distribution for SF solution.…”