Energy-consistent formulation of the pressure-free two-fluid model

The pressure-free two-fluid model (PFTFM) is a recent reformulation of the one-dimensional two-fluid model (TFM) for stratified incompressible flow in ducts (including pipes and channels), in which the pressure is eliminated through intricate use of the volume constraint. The disadvantage of the PFTFM was that the volumetric flow rate had to...

Transient Thermal Modelling of Cooling Methods in Green Bi-Propellant Thrusters for CubeSat Applications: A numerical and experimental comparison of regenerative cooling and radiation cooling in a CubeSat scale propulsion system

The Dutch/New Zealand based aerospace company Dawn aerospace has developed a 0.5N green bi-propellant propulsion system for use in CubeSat applications called the PM200. This thruster uses gaseous nitrous oxide and propylene as propellants. Currently, the burn time of this thruster is limited to 10 seconds after which cool down of the thruster...

Accuracy aspects of conventional discretization methods for scalar transport with nonzero divergence velocity field arising from the energy balance equation

We are concerned with the numerical solution of a linear transport problem with nonzero divergence velocity field that originates from the spectral energy balance equation describing the evolution of wind waves and swells in coastal seas. The discretization error of the commonly used first-order upwind finite difference and first-order vertex...

MultiScale finite volume method for finite-volume based poromechanics simulations

We propose a multiscale finite volume method (MSFV) for simulation of coupled flow-deformation in heterogeneous porous media under elastic deformation (i.e., poroelastic model). The fine-scale fully resolved system of equations is obtained based on a conservative finite-volume method in which the displacement and pore pressure unknowns are...

Combining the Augmented Lagrangian Preconditioner withe the SIMPLE Schur Complement Approximation

The augmented Lagrangian (AL) preconditioner and its variant have been successfully applied to solve saddle point systems arising from the incompressible Navier-Stokes equations discretized by the finite element method. Attractive features are the purely algebraic construction and robustness with respect to the Reynolds number and mesh renement....

Finite Volume Method for Poroelasticity

When modelling fluid fl ow in subsurface, the impact of solid deformation on fluid fl ow is often oversimplified/neglected in reservoir simulators. It is assumed that solid volume/s-tate of stress is a function of fluid pressure, while the opposite effect is not considered. This assumption is made mainly to reduce computational costs and...

Morphological modeling using a fully coupled, total variation diminishing upwind-biased centered scheme

High-resolution morphological modeling of fluvial processes with complex, rapidly varying flows has been limited so far by model accuracy or computational efficiency. One of the most widely used numerical algorithms is based on the total variation diminishing method, solved by either upwind or centered approaches. An upwind scheme preserves high...

A Hybrid Five-Point Finite Difference Scheme for Convection-Diffusion Equations

In this paper, some five-point finite difference schemes for steady convection-diffusion problems are presented. To begin with, we use the finite volume method (FVM) to discretize the convection-diffusion equation. After that, we present two five-point difference schemes for the approximation of the first order derivatives on faces, one of which...

A multilevel adaptive multiscale finite volume method for steady compressible flows

An implicit multilevel finite volume solver on adaptively refined quadtree meshes is presented for the solution of steady state flow problems. The nonlinear problem arising from the implicit time discretization is solved by an adaptive FAS multigrid method. Local grid adaptation is performed by means of a multiscale-based strategy. For this...

Adaptive sonic boom sensitivity analysis

This paper presents an accurate approach to simulate the sonic boom of a supersonic aircraft. The near field flow is modeled by the conservative Euler equations and is solved using a finite volume approach on adapted unstructured tetrahedral meshes. Then, from the CFD solution, the pressure distribution under the aircraft is extracted and used...

The Weighted Least Square Scheme for Multidimensional Flows

This article describes the development of a high order finite volume method for the solution of transonic flows. The high order of accuracy is achieved by a reconstruction procedure similar to the weighted essentially non-oscillatory schemes (WENO). On the contrary to the WENO schemes, the weighted least square (WLSQR) scheme is easily...

ALMD: A modeling environment for ILES

Further development of Large Eddy Simulation faces as major obstacle the strong coupling between subgrid-scale model and the truncation error of the numerical discretization. Recent analyzes indicate that for certain discretizations and certain flow configurations the truncation error itself can act as implicit SGS model. Relevant...

Design and flow analysis of radial and mixed flow turbine volutes

Radial and mixed flow turbines which are an important component of a turbocharger consist essentially of a volute, a rotor and a diffuser. Vaneless volute turbines, which have reasonable performance and low cost, are the most used in turbochargers for automotive engines. Care has to be done in the design of the volute, whose function is to...

A three-dimensional finite volume method for incompressible Navier-Stokes equations on unstructured hybrid staggered grids

In this work, a new method was described for spatial discretization of threedimensional Navier Stokes equations in their primitive form, on unstructured, staggered grids. Velocities were placed on the cell faces and pressure in cell centers and were linked with the projection method. Thanks to the variable arrangement, no stabilization procedure...

Superlinearly Convergent Unstructured Staggered Schemes for Compressible and Incompressible Flows

The major issue addressed in this thesis is the development of a Mach-uniform method that uses a staggered scheme on planar unstructured grids with triangular cells, that has a superlinear rate of convergence. In our staggered grid, the normal velocity components are associated with cell faces, whereas scalar variables are assigned to cell...

Wave drag determination in the transonic full-potential flow code matrics

The mathematical background is described of a method that is currently being developed at NLR to calculated wave drag in transonic potential flow. The method is a generalization and extension of Garabedian's and McFadden's idea of determining wave drag by volume-integration of the artificial viscosity. The generalization of Garabedian's and...

Numerical evaluation of an efficient ROE scheme and chemical models for chemically reacting nozzle flows in thermal equilibrium

An efficient Roe-type flux-difference scheme for chemically reacting inviscid compressible flow in thermal equilibrium is presented. The numerical scheme is validated. Three well known chemical models are compared. The set of testcases concerned quasi one-dimensional hypersonic nozzle flows, with and without strong normal Shockwaves.

ARSPNS: a method to calculate steady and unsteady potential flow about fixed and rotating lifting and nonlifting bodies

A new method ARNSPNS is described for the calculation of steady and time-linearized unsteady incompressible potential flow about arbitrary lifting and nonlifting bodies in an arbitrary mean steady flow field, including rotation. The method belongs to the category of the so-called panel methods. Applications have been made to wind turbines...