One-dimensional three-fluid flows

2007 ◽  
pp. 325-406
Author(s):  
Nikolay I. Kolev
Keyword(s):  
Fluid Flows ◽  
One Dimensional

scholarly journals AN IMPROVED MODEL FOR REDUCED-ORDER PHYSIOLOGICAL FLUID FLOWS

2012 ◽  
Vol 12 (03) ◽  
pp. 1250052 ◽  
Author(s):  
OMER SAN ◽  
ANNE E. STAPLES
Keyword(s):  
Fluid Flows ◽  
Momentum Equation ◽  
System Level ◽  
Arterial Tree ◽  
Reduced Order ◽  
One Dimensional ◽  
Proposed Model ◽  
Nonlinear Coupled System ◽  
Physiological Fluid ◽  
Physiological Systems

An improved one-dimensional mathematical model based on the Pulsed Flow Equations (PFE) is derived by integrating the axial component of the momentum equation over the transient Womersley velocity profile, providing a dynamic momentum equation whose coefficients are smoothly varying functions of the spatial variable. The resulting momentum equation along with the continuity equation and pressure-area relation form our reduced-order model for physiological fluid flows in one dimension and are aimed at providing accurate and fast-to-compute global models for physiological systems represented as networks of quasi one-dimensional fluid flows. The consequent nonlinear coupled system of equations is solved by the Lax-Wendroff scheme and is then applied to an open model arterial network of the human vascular system containing the largest 55 arteries. The proposed model with functional coefficients is compared with current classical one-dimensional theories which assume steady state Hagen-Poiseuille velocity profiles, either parabolic or plug-like, throughout the whole arterial tree. The effects of the nonlinear term in the momentum equation and different strategies for bifurcation points in the network, as well as the various lumped parameter outflow boundary conditions for distal terminal points are also analyzed. The results show that the proposed model can be used as an efficient tool for investigating the dynamics of reduced-order models of flows in physiological systems and would, in particular, be a good candidate for the one-dimensional, system-level component of geometric multiscale models of physiological systems.

Quasi-1D Unsteady Conjugate Module for Rocket Engine and Propulsion System Simulations

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Bryan T. Campbell ◽  
Roger L. Davis
Keyword(s):  
Transient Flow ◽  
Rocket Engine ◽  
Fluid Flows ◽  
Solution Procedure ◽  
Test Cases ◽  
Rocket Engines ◽  
Propulsion Systems ◽  
One Dimensional ◽  
Real Fluid ◽  
Software Modules

A new quasi-one-dimensional procedure (one-dimensional with area change) is presented for the transient solution of real-fluid flows in lines and volumes including heat transfer effects. The solver will be integrated into a larger suite of software modules developed for simulating rocket engines and propulsion systems. The solution procedure is coupled with a state-of-the-art real-fluid property database so that both compressible and incompressible fluids may be considered using the same procedure. The numerical techniques used in this procedure are described. Test cases modeling transient flow of nitrogen, water, and hydrogen are presented to demonstrate the capability of the current technique.

Remapping-Free Adaptive GRP Method for Multi-Fluid Flows I: One Dimensional Euler Equations

2014 ◽  
Vol 15 (4) ◽  
pp. 1029-1044 ◽  
Author(s):  
Jin Qi ◽  
Yue Wang ◽  
Jiequan Li
Keyword(s):  
Euler Equations ◽  
Compressible Flows ◽  
Fluid Flows ◽  
Computational Grids ◽  
Material Interfaces ◽  
Material Interface ◽  
One Dimensional ◽  
Two Fluids ◽  
Numerical Fluxes ◽  
Volume Method

AbstractIn this paper, a remapping-free adaptive GRP method for one dimensional (1-D) compressible flows is developed. Based on the framework of finite volume method, the 1-D Euler equations are discretized on moving volumes and the resulting numerical fluxes are computed directly by the GRP method. Thus the remapping process in the earlier adaptive GRP algorithm [17,18] is omitted. By adopting a flexible moving mesh strategy, this method could be applied for multi-fluid problems. The interface of two fluids will be kept at the node of computational grids and the GRP solver is extended at the material interfaces of multi-fluid flows accordingly. Some typical numerical tests show competitive performances of the new method, especially for contact discontinuities of one fluid cases and the material interface tracking of multi-fluid cases.

An elliptic-parabolic free boundary problem: continuity of the interface

1987 ◽  
Vol 106 (3-4) ◽  
pp. 327-339 ◽  
Author(s):  
J. Hulshof
Keyword(s):  
Porous Media ◽  
Weak Solution ◽  
Parabolic Equations ◽  
Parabolic Problem ◽  
Fluid Flows ◽  
One Dimensional ◽  
The Maximum Principle ◽  
Partially Saturated ◽  
Physical Background ◽  
Essential Assumption

SynopsisIn this paper we establish continuity of the interface of the weak solution to an elliptic-parabolic problem. The physical background is the theory of partially saturated fluid flows in porous media. Our method is based on the maximum principle for parabolic equations. An essential assumption is that the flow is one-dimensional.

Entanglement transitions in one-dimensional confined fluid flows

2018 ◽  
Vol 50 (1) ◽  
pp. 011416
Author(s):  
K C Millett ◽  
E Panagioutou
Keyword(s):  
Fluid Flows ◽  
One Dimensional ◽  
Confined Fluid

Modelling and testing of a hydrodynamic clutch filled with electrorheological fluid in varying degree

2019 ◽  
Vol 30 (4) ◽  
pp. 649-660 ◽  
Author(s):  
Artur Olszak ◽  
Karol Osowski ◽  
Zbigniew Kęsy ◽  
Andrzej Kęsy
Keyword(s):  
Steady State ◽  
Mathematical Models ◽  
Experimental Research ◽  
Fluid Flows ◽  
Electrorheological Fluid ◽  
Angular Speed ◽  
Working Fluid ◽  
Filling Degree ◽  
One Dimensional ◽  
Working Space

The article concerns steady-state characteristics of a hydrodynamic clutch with electrorheological working fluid controlled by changes in strength of electric field and changes in the filling degree. The characteristics were obtained by experimenting, as well as calculations based on one-dimensional mathematical models. While creating the mathematical models, factors taken into consideration included differences between methods controlling the clutch, as well as various ways the working fluid flows in the clutch’s working space, depending on the relation of angular speed of rotors. The resultant mathematical models were verified with experimental research.

Modeling Laminar Fluid Flows in Rectangular Vapor Grooves of Evaporators Used in Loop Heat Pipes

2010 ◽  
Author(s):  
Nirmalakanth Jesuthasan ◽  
B. Rabi Baliga
Keyword(s):  
Pressure Drop ◽  
Three Dimensional ◽  
Fluid Flows ◽  
Heat Pipes ◽  
Cost Effective ◽  
Operating Conditions ◽  
Pressure Drops ◽  
One Dimensional ◽  
Loop Heat Pipes ◽  
Dimensional Models

Loop heat pipes (LHPs) are devices in which capillary forces in a wick and liquid-vapor phase-change phenomena are used to achieve continuous and relatively high rates of transfer of thermal energy from a heat source to a heat sink. Quasi one-dimensional models of the fluid flow and heat transfer within LHPs, with empirical correlations as inputs, are commonly used as the basis of cost-effective computer simulations for the design and optimization of these devices for specific applications. The focus in this work is on laminar fluid flows in straight rectangular vapor grooves of flat evaporators used in LHPs. The pressure drops for such fluid flows are computed in available quasi one-dimensional models of LHPs using correlations for a friction factor that applies strictly only in the fully-developed region of flows in straight rectangular ducts with impermeable walls. The resulting errors can become serious if the pressure drop in the vapor grooves is a significant contributor to the overall pressure drop in the LHP. Thus, to enhance the capabilities of current quasi one-dimensional models of LHPs, more accurate correlations for predicting the aforementioned pressure drop are needed. In this work, a three-dimensional parabolic finite volume method is used to simulate laminar Newtonian fluid flows in straight rectangular vapor grooves of flat evaporators, for a representative range of LHP operating conditions. The mathematical model, computational methodology, results, and suitable correlations for the pressure drops are presented and discussed in this paper.

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