scholarly journals Effects of Pulse Interval and Dosing Flux on Cells Varying the Relative Velocity of Micro Droplets and Culture Solution

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 119 ◽  
Author(s):  
Zhanwei Wang ◽  
Kun Liu ◽  
Jiuxin Ning ◽  
Shulei Chen ◽  
Ming Hao ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Mass Fraction ◽  
Pulse Interval ◽  
Culture Solution ◽  
Cell Surfaces ◽  
Fraction Distribution ◽  
Pdms Chip ◽  
Solution Velocity ◽  
The Mathematical Model ◽  
Delivery Efficiency

Microdroplet dosing to cell on a chip could meet the demand of narrow diffusion distance, controllable pulse dosing and less impact to cells. In this work, we studied the diffusion process of microdroplet cell pulse dosing in the three-layer sandwich structure of PDMS (polydimethylsiloxane)/PCTE (polycarbonate) microporous membrane/PDMS chip. The mathematical model is established to solve the diffusion process and the process of rhodamine transfer to micro-traps is simulated. The rhodamine mass fraction distribution, pressure field and velocity field around the microdroplet and cell surfaces are analyzed for further study of interdiffusion and convective diffusion effect. The cell pulse dosing time and drug delivery efficiency could be controlled by adjusting microdroplet and culture solution velocity without impairing cells at micro-traps. Furthermore, the accuracy and controllability of the cell dosing pulse time and maximum drug mass fraction on cell surfaces are achieved and the drug effect on cells could be analyzed more precisely especially for neuron cell dosing.

Mass transfer dominated by thermal diffusion in laminar boundary layers

1997 ◽  
Vol 336 ◽  
pp. 379-409 ◽  
Author(s):  
PEDRO L. GARCÍA-YBARRA ◽  
JOSE L. CASTILLO
Keyword(s):  
Mass Transport ◽  
Boundary Layers ◽  
Thermal Diffusion ◽  
Mass Fraction ◽  
Soret Effect ◽  
Second Order ◽  
Brownian Diffusion ◽  
Diffusion Transport ◽  
Laminar Boundary Layers ◽  
Fraction Distribution

The concentration distribution of massive dilute species (e.g. aerosols, heavy vapours, etc.) carried in a gas stream in non-isothermal boundary layers is studied in the large-Schmidt-number limit, Sc[Gt ]1, including the cross-mass-transport by thermal diffusion (Ludwig–Soret effect). In self-similar laminar boundary layers, the mass fraction distribution of the dilute species is governed by a second-order ordinary differential equation whose solution becomes a singular perturbation problem when Sc[Gt ]1. Depending on the sign of the temperature gradient, the solutions exhibit different qualitative behaviour. First, when the thermal diffusion transport is directed toward the wall, the boundary layer can be divided into two separated regions: an outer region characterized by the cooperation of advection and thermal diffusion and an inner region in the vicinity of the wall, where Brownian diffusion accommodates the mass fraction to the value required by the boundary condition at the wall. Secondly, when the thermal diffusion transport is directed away from the wall, thus competing with the advective transport, both effects balance each other at some intermediate value of the similarity variable and a thin intermediate diffusive layer separating two outer regions should be considered around this location. The character of the outer solutions changes sharply across this thin layer, which corresponds to a second-order regular turning point of the differential mass transport equation. In the outer zone from the inner layer down to the wall, exponentially small terms must be considered to account for the diffusive leakage of the massive species. In the inner zone, the equation is solved in terms of the Whittaker function and the whole mass fraction distribution is determined by matching with the outer solutions. The distinguished limit of Brownian diffusion with a weak thermal diffusion is also analysed and shown to match the two cases mentioned above.

scholarly journals Increasing Oxygen Mass Fraction in Blind Headings of a Plateau Metal Mine by Oxygen Supply Duct Design: A CFD Modelling Approach

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zijun Li ◽  
Shuqi Zhao ◽  
Rongrong Li ◽  
Yilong Huang ◽  
Yu Xu ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Oxygen Supply ◽  
Ventilation System ◽  
Western China ◽  
Cfd Modelling ◽  
Supply Effect ◽  
Metal Mine ◽  
Optimum Height ◽  
Fraction Distribution ◽  
Duct Design

Hypoxia problem has always been a difficult point in plateau tunneling projects. To solve this problem, a blind heading face in a plateau metal mine in western China was taken as the physical model, and the computational fluid dynamics was used to analyze the oxygen mass fraction distribution and oxygen-increasing effect in 1 m, 3 m, and 5 m roadway sections from the heading face. The optimal ventilation system was first built to obtain the optimum height and length of the airflow ducts. Then different cases with various oxygen supply duct designs were built in 2 scenarios. The results found that different oxygen supply duct design has significant influence on the oxygen distribution in the heading face. Also, each design has different optimal height of oxygen outlet. The oxygen supply effect is best when some small holes are made in the oxygen supply duct to diffuse oxygen to the working surface. The finding of this paper is helpful for effective and economical oxygen supply in roadway excavation of plateau metal mine and tunnel.

scholarly journals Locus of first crystals on the evaporative surface of a vertically textured porous medium

2018 ◽  
Vol 81 (1) ◽  
pp. 11102 ◽  
Author(s):  
Babacar Diouf ◽  
Sandrine Geoffroy ◽  
Ariane Abou Chakra ◽  
Marc Prat
Keyword(s):  
Porous Medium ◽  
Mass Fraction ◽  
Saline Solution ◽  
Liquid Volume ◽  
Porous Domain ◽  
Fraction Distribution ◽  
Initial Salt ◽  
Medium Column ◽  
Very High

The evaporation of a saline solution from a heterogeneous porous medium formed by the assembly of a coarse medium column and a fine medium column is studied numerically. We concentrate on the locus of the formation of first crystals on the evaporative surface from the computation of the ion mass fraction distribution at the surface prior to the efflorescence development. Two basic situations considered in previous works, namely the evaporation–wicking situation and the drying situation are considered. The study makes clear that each situation leads to a markedly different locus of the efflorescence formation, except, however, for very high initial salt concentrations. The study emphasizes the key-role of the velocity field induced in the porous domain in the case of the evaporation–wicking situation. In the case of the drying situation, a key aspect lies in the local increase in the ion mass fraction due to the local desaturation, i.e. the local shrinking of the liquid volume containing the ions.

scholarly journals Flow Induced Vibration of Cantilever Tapered Pipes Transporting Fluid

2021 ◽  
Vol 16 ◽  
pp. 8-13
Author(s):  
Mohamed Gaith
Keyword(s):  
Cross Section ◽  
Mass Fraction ◽  
Natural Frequencies ◽  
Fluid Velocity ◽  
Inviscid Fluid ◽  
Sectional Area ◽  
Flow Induced Vibration ◽  
Cross Sectional ◽  
Uniform Cross Section ◽  
The Mathematical Model

A cantilevered tapered slender pipe conveying an incompressible, inviscid fluid of one material is not a conserved system. For certain large fluid velocity, the pipe with uniform cross section would go unstable via flutter Hopf bifurcation. In this paper, the flow induced vibration for cantilever tapering pipe transporting a fluid is presented. Euler Bernoulli and Hamilton’s theories are applied to develop the mathematical model which will be solved using well known Galerkan’s procedure. The effect of smooth tapering of the circular cross sectional area, flow velocity and pipe to fluid mass fraction on the complex natural frequencies and stability will be investigated.

Theoretical Model of Bubble Growth in Superheated Ethanol-Water Mixture

2019 ◽  
Author(s):  
Chang Cai ◽  
Hong Liu ◽  
Xi Xi ◽  
Ming Jia ◽  
Weilong Zhang ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Bubble Growth ◽  
Mass Fraction ◽  
Bubble Radius ◽  
Bubble Surface ◽  
Mass Diffusion ◽  
Growth Characteristics ◽  
Initial Mass ◽  
Water Mixture ◽  
Fraction Distribution

Abstract A novel model was developed to investigate the bubble growth characteristics in uniformly superheated ethanol-water (EtOH-H2O) mixture. The influence of the mass fraction of ethanol was discussed in detail. In the proposed model, the energy equation and the component diffusion equation for the liquid were respectively coupled with quadratic temperature and mass fraction distribution within the thermal and concentration boundary layers. The non-random two-liquid equation (NRTL) was adopted to obtain the vapor-liquid equilibrium of the binary mixture at the bubble surface. The comparison between the current calculated bubble radius with the available experimental data demonstrates the accuracy of the bubble growth model. The maximum mass diffusion limited growth rate was also proposed to quantify and illustrate the effect of mass diffusion on bubble growth. The results showed that the later stage of bubble growth in a binary mixture is controlled by both mass diffusion and heat transfer. The bubble growth characteristics strongly depend on the initial mass fraction of ethanol. Within a large concentration range, a higher content of ethanol is adverse to bubble growth at a constant superheat degree. The effect of mass diffusion on bubble growth becomes weaker with an increased initial mass fraction of ethanol.

Sign in / Sign up

Export Citation Format

Share Document