Effect of Surface Conduction on Propagation of Ion-Concentration Shock Waves in Isotachophoresis

2015 ◽  
Author(s):  
Mayank Khichar ◽  
Romir Moza ◽  
Supreet Singh Bahga
Keyword(s):  
Shock Waves ◽  
Numerical Solutions ◽  
Ionic Species ◽  
Ion Concentration ◽  
Expansion Waves ◽  
Electrophoretic Techniques ◽  
Electrophoretic Transport ◽  
Wall Charge ◽  
Surface Conduction ◽  
Effect Of Surface

Isotachophoresis (ITP) is a widely used nonlinear electrophoretic technique for preconcentration and separation of ionic species. Typically, ITP is performed in microchannels where the effect of surface conduction due to electric double layer (EDL) at channel walls is negligible compared to bulk conduction. However, when electrophoretic techniques such as ITP are integrated in nanochannels or shallow microchannels, surface conduction can alter bulk electrophoretic transport. The existing mathematical models for multispecies electrophoretic transport do not account for the competing effects of surface and bulk conduction. We present a mathematical model for multispecies electrophoretic transport incorporating the effects of surface conduction on bulk ion-transport. Our one-dimensional model is capable of describing electrophoretic systems consisting of arbitrarily large number of co-ions, having same charge polarity as the wall charge, and a single counter-ion. Based on numerical solutions of the governing equations, we show that unlike in conventional ITP where surface conduction is negligible, the zone concentrations do not obey the Kohlrausch regulating function when surface conduction is prominent. Moreover, our simulations show that surface conduction alters the propagation speeds of ion-concentration shock waves in ITP. In addition, surface conduction results in additional shock and expansion waves in ITP which are otherwise not present in conventional ITP.

scholarly journals Nematic Dispersive Shock Waves from Nonlocal to Local

2021 ◽  
Vol 11 (11) ◽  
pp. 4736
Author(s):  
Saleh Baqer ◽  
Dimitrios J. Frantzeskakis ◽  
Theodoros P. Horikis ◽  
Côme Houdeville ◽  
Timothy R. Marchant ◽  
...  
Keyword(s):  
Shock Wave ◽  
Liquid Crystals ◽  
Shock Waves ◽  
Numerical Solutions ◽  
Wave Structure ◽  
Beam Power ◽  
Input Beam ◽  
Shock Wave Structure ◽  
Wave Solutions ◽  
Modulation Theory

The structure of optical dispersive shock waves in nematic liquid crystals is investigated as the power of the optical beam is varied, with six regimes identified, which complements previous work pertinent to low power beams only. It is found that the dispersive shock wave structure depends critically on the input beam power. In addition, it is known that nematic dispersive shock waves are resonant and the structure of this resonance is also critically dependent on the beam power. Whitham modulation theory is used to find solutions for the six regimes with the existence intervals for each identified. These dispersive shock wave solutions are compared with full numerical solutions of the nematic equations, and excellent agreement is found.

scholarly journals The effect of surface tension on steadily translating bubbles in an unbounded Hele-Shaw cell

2017 ◽  
Vol 473 (2201) ◽  
pp. 20170050 ◽  
Author(s):  
Christopher C. Green ◽  
Christopher J. Lustri ◽  
Scott W. McCue
Keyword(s):  
Surface Tension ◽  
Numerical Solutions ◽  
Bubble Velocity ◽  
Number Of Solutions ◽  
Branch Number ◽  
Single Solution ◽  
Countably Infinite ◽  
Prime Function ◽  
Hele Shaw Cell ◽  
Effect Of Surface

New numerical solutions to the so-called selection problem for one and two steadily translating bubbles in an unbounded Hele-Shaw cell are presented. Our approach relies on conformal mapping which, for the two-bubble problem, involves the Schottky-Klein prime function associated with an annulus. We show that a countably infinite number of solutions exist for each fixed value of dimensionless surface tension, with the bubble shapes becoming more exotic as the solution branch number increases. Our numerical results suggest that a single solution is selected in the limit that surface tension vanishes, with the scaling between the bubble velocity and surface tension being different to the well-studied problems for a bubble or a finger propagating in a channel geometry.

Influence of Skewing of Contact Face on Performance of Wave Rotor Refrigerators and Superchargers

2013 ◽  
Author(s):  
Yuqiang Dai ◽  
Fengxia Liu ◽  
Jintao Wu ◽  
Wei Wei ◽  
Dapeng Hu ◽  
...  
Keyword(s):  
High Pressure ◽  
Mach Number ◽  
Shock Waves ◽  
Rotational Speed ◽  
Channel Width ◽  
Wave Rotor ◽  
Coriolis Forces ◽  
Local Loss ◽  
Expansion Waves ◽  
Pressure Port

As a novel generation of rotational gas wave machines, wave rotor machines such as wave rotor refrigerators (WRR) and wave rotor superchargers (WRS) are unsteady flow devices. In their passages two gas streams (with different pressure or even different phases) comes into direct contact can exchange energy due to the movement of shock waves and expansion waves. A detailed study shows that, when rotor channels open to the high pressure port gradually, the contact face in rotor channels inevitably skews, which is always accompanied with reflection of shockwaves. This causes very large energy dissipation and influences adversely on the refrigeration performance of WRR or the supercharging performance of WRS. In this work, factors such as centrifugal forces, Coriolis forces, gradual channel opening and gradual channel closing, etc, which influence the wave transportation and skewing of shock waves and contact faces are studied by means of computational fluid dynamics and experiments. The skewing of contact faces causes uneven distribution of velocity and large local loss. With rotation Mach number smaller than 0.3, the skewing of contact face can be alleviated. To reduce the adverse influence of rotation Mach number, a smaller rotor channel width or higher rotational speed is necessary. The rotation effect plays an important role for the skewing of gas discontinuities. Both the centrifugal and Coriolis forces of wave rotor cannot be ignored with the Rossby number of 1.3∼3.5. To reduce the skewing loss of contact face, a lower rotational speed seems necessary. The rotation speed of wave rotors has dialectical influences on the skewing of shock waves and contact faces. The jetting width of high pressure port is the key factor of the gradual opening of rotor channels. A feasible way to reduce skewing losses of gas waves is to optimize the ratio between high pressure port width and channel width. The validation experiments have got at least 3∼5% rise of isentropic efficiency for WRRs.

Calculation of Surface Roughness Effects on Air-Riding Seals

2002 ◽  
Author(s):  
C. Guardino ◽  
J. W. Chew ◽  
N. J. Hills
Keyword(s):  
Surface Roughness ◽  
Compressible Flows ◽  
Reynolds Equation ◽  
Incompressible Flows ◽  
Numerical Solutions ◽  
Cfd Analysis ◽  
Roughness Effects ◽  
Stationary Wall ◽  
Comparative Results ◽  
Effect Of Surface

The effects of surface roughness on air-riding seals are investigated here using the Rayleigh-pad as an example. Both incompressible and compressible flows are considered using both CFD analysis and analytical/numerical solutions of the Reynolds equation for various 2D or 3D roughness patterns on the stationary wall. A ‘unit-based’ approach for incompressible flows has also been employed and is shown to be computationally much less expensive than the full-geometry solution. Results are presented showing the effect of surface roughness on the net lift force. The effects of varying the Reynolds number are demonstrated, as well as comparative results for static stiffness.

scholarly journals Effect of surface roughness on nonlinear reflection of weak shock waves

2019 ◽  
Vol 146 (5) ◽  
pp. EL438-EL443
Author(s):  
Maria M. Karzova ◽  
Thomas Lechat ◽  
Sébastien Ollivier ◽  
Didier Dragna ◽  
Petr V. Yuldashev ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Shock Waves ◽  
Weak Shock ◽  
Nonlinear Reflection ◽  
Effect Of Surface

scholarly journals Changes in the kinetic behaviour of threonine transport into Trypanosoma brucei elicited by variation in hydrogen ion concentration

1977 ◽  
Vol 164 (1) ◽  
pp. 15-25 ◽  
Author(s):  
H. Paul Voorheis
Keyword(s):  
Binding Site ◽  
Trypanosoma Brucei ◽  
Substrate Binding ◽  
Ionic Species ◽  
Ion Concentration ◽  
Amino Group ◽  
Hydrogen Ion Concentration ◽  
Substrate Binding Site ◽  
Kinetic Behaviour ◽  
Substrate Complex

1. The dependence of V and V/Km for threonine transport into Trypanosoma brucei upon the external concentration of H+ was studied. 2. Two ionizing groups, the α-amino group of the substrate and a group at the substrate-binding site of the carrier, were found to influence the observed kinetic behaviour of transport. 3. The pK of the group at the substrate-binding site on the free carrier was found to be 6.95 at 30°C and to be temperature-dependent; its heat of ionization was −63.8kJ, which is outside the range for most proton dissociations and suggests a significant contribution from some other source, possibly the remainder of the carrier or the membrane environment. 4. Binding of substrate caused the pK of its α-amino group to shift to a higher value, whereas that of the carrier group shifted to a lower value (6.65 at 30°C). 5. The ionic interaction between substrate and carrier appeared to be involved in the stabilizing of the protonated substrate and the species of the carrier–substrate complex required for the membrane-translocation step. 6. The same ionic species of carrier–substrate complex is required for both substrate dissociation and translocation of the substrate through the membrane. 7. H+ symport or antiport did not occur during threonine uptake.

Expansion shock waves in numerical solutions of gasdynamic problems

2009 ◽  
Vol 1 (1) ◽  
pp. 21-30 ◽  
Author(s):  
M. V. Abakumov ◽  
S. I. Mukhin ◽  
Yu. P. Popov ◽  
D. V. Rogozhkin
Keyword(s):  
Shock Waves ◽  
Numerical Solutions ◽  
Gasdynamic Problems
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