Numerical Simulation Of Liquid Flow Research Articles

Simultaneous PIV/LIF-PIV measurements and numerical simulation of liquid flow and ambient gas flow for transient diesel spray

The characteristics of spray/ambient gas flow and the turbulent mixing process significantly influence the subsequent combustion feature. There are some related studies on the simultaneous measurement of spray liquid/gas phase flow using optical diagnosis techniques. However, the two-phase flow characteristics of the transient Diesel spray have not been discussed in detail, few works have verified the measuring accuracy of the methods. This study proposes a PIV/LIF-PIV measuring method for simultaneously investigating the liquid/gas flow of transient Diesel spray. The experimental process and effects of imaging parameters/digital image processing method on the measuring accuracy are discussed based on the detectability of cross-correlation peak. The characteristics of the local turbulent mixing of liquid/gas flow for Diesel spray are presented. Numerical simulation using the Large-Eddy Simulation (LES) Eulerian-Lagrangian method is also carried out for extending the understanding regarding the liquid/gas phase flow process. The results indicate that the upstream vortex structures of spray flow lead to the random direction of velocity vectors at the tip, which is related to the shot-by-shot variation of spray structure at early timing after SOI. A similar streamline of spray flow and ambient gas flow could be observed in the spray region especially at 2.0 ms ASOI, which implies the gaseous phase is accelerated rapidly by the internal spray droplets as soon as entering the spray boundary, and both phases reach a “balanced state” at the end of the injection period. Similar results could be derived from the simulation results, the position where the maximum spray velocity exists is quite different because of the randomness of the instantaneous flow. An improved quasi-dimensional velocity predicting model that accounts for the spatial variation of velocity distribution is also developed.

Numerical investigation on fluid flow and convective heat transfer in a microchannel heat sink with fan-shaped cavities and ribs

In the present study, a detailed numerical simulations of liquid flow in microchannel heat sink with four different geometry of ribs: rectangular (RR), backward triangular (BTR), forward triangular (FTR) and diamond (DR) arranged symmetrically inside reentrant fan shaped cavities (FC) on side walls has been conducted and compared with smooth channel (SC) to acquire fluid flow and heat transfer characteristics between Reynolds numbers of 136−588. The local pressure, temperature and heat transfer coefficients were determined to understand the convective heat transfer regimes and to analyze local flow behavior. The three-dimensional conjugate heat transfer model, investigation is done extensively to identify the influence of geometrical parameters towards augmenting thermal performance with parametric optimization. Evolved governing equations are solved by using SIMPLEC algorithm. Attempt has been made to improve heat extraction ability with reasonable pressure drop by replacing the existing simple design of microsink. It is observed that Nusselt number and friction factor are in good agreement with previous experimental data. Based on detailed parametric study, it was found that FC-RR is good in achieving maximum Nusselt number, but due to higher pressure drop penalty giving lower performance. Out of four proposed, FC-DR is conferring upstanding balance between heat transfer, pressure drop and giving the best thermal performance of 1.97 at Re = 391.47.

CFD simulation of bubble in flow field: Investigation of dynamic interfacial behaviour in presence of surfactant molecules

This work presents the results of numerical simulation of liquid flow on a static bubble. Velocity and surfactant concentration profiles of the liquid around a bubble exposed in flow field were estimated via unsteady CFD solution. Governing equations are the Navier-Stokes and conservation of mass in the liquid bulk and at the interface. Resulted profiles of surfactant concentration and velocity in the liquid bulk are used to determine the dynamic surface tension data via two adsorption isotherms of Langmuir and Frumkin. Data of dynamic surface tension were validated via experimental data of “bubble in flow field” protocol. Surface concentrations of surfactants were also numerically estimated. At longer flow times, surface concentration increases due to adsorption and accumulation of surfactants at the interface. The rate of mass transfer is increased by development of velocity profile around the bubble surface. Steady state was reached about 36 s after flow starts.

Efficient Permeability Measurement and Numerical Simulation of the Resin Flow in Low Permeability Preform Fabricated by Automated Dry Fiber Placement

We propose a new experimental method using a Hassler cell and air injection to measure the permeability of fiber preform while avoiding a race tracking effect. This method was proven to be particularly efficient to measure very low through-thickness permeability of preform fabricated by automated dry fiber placement. To validate the reliability of the permeability measurement, the experiments of viscous liquid infusion into the preform with or without a distribution medium were performed. The experimental data of flow front advancement was compared with the numerical simulation result using the permeability values obtained by the Hassler cell permeability measurement set-up as well as by the liquid infusion experiments. To address the computational cost issue, the model for the equivalent permeability of distribution medium was employed in the numerical simulation of liquid flow. The new concept using air injection and Hassler cell for the fiber preform permeability measurement was shown to be reliable and efficient.

Application of Lattice-Boltzmann Method to Numerical Simulation of Liquid Flow in Microchannel

Application of Lattice-Boltzmann Method to Numerical Simulation of Liquid Flow in Microchannel

Development of Medical and Technical Requirements and Simulation of the Flow−Pressure Characteristics of the Sputnik Pediatric Rotary Blood Pump

This article discusses the first stages in the development of the Sputnik implantable pediatric rotary blood pump (Sputnik IPRBP). The requirements for the group of patients for whom the Sputnik IPRBP was developed were formulated. The design of the Sputnik IPRBP consists of a fixed flow tube, a straightener at the inflow, an impeller with an embedded magnet rotating at a rate of several thousand rpm, and a fixed diffuser on the output. Results of numerical simulation of liquid flow in the Sputnik IPRBP run in the Fluent ANSYS 16.2 hydrody-namics system are presented.

Experimental and numerical simulation of discrete liquid flow in a packed bed

This paper presents a combined experimental and numerical method to simulate the liquid flow in a packed bed. Two types of the experiments, i.e. liquid percolation without gas flow and liquid flow with gas cross flow, were conducted using a three- or two-dimensional cold model, respectively. A mathematical model has been proposed for the numerical simulation of the liquid flow. This model was developed using a force balance approach combined with stochastic considerations, in which the liquid flow was treated as a discrete phase with stochastic dispersion based on the experimental observations. Accordingly, the interactions between liquid and the packed bed, and liquid and gas have been experimentally investigated and then were used to determined the model parameters involved in the model. The behavior of the liquid flow in packed beds can numerically be simulated using the proposed model. A reasonable agreement has been achieved between the model predictions and the experimental measurements.

Numerical simulations of liquid flow on spiral concentrators

Mathematical models can assist in the design of spiral concetrator and the optimization of their operation. This study represents a first step in the development of a mechanistic model of the operation of a spiral. A helical coordinate system appropriate for a simplified spiral is presented, together with detail of the equations of continuity and motion in this coordinate system. An outline of the numerical method used to find the fully developed laminar flow of a Newtonian liquid on spiral, a comparison of the simulations with experimental data, simulations to show the effect of geometry on flow on spiral are also presented.