Sökning: "Multi-phase flow"

Visar resultat 16 - 20 av 28 avhandlingar innehållade orden Multi-phase flow.

1. 16. A Realizable Hybrid Mixture-Bubble Model for Cavitating Flows

   Författare :Ebrahim Ghahramani; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Multi-scale model; Homogeneous mixture model; Cavitation; Disperse multiphase flow; Eulerian-Lagrangian model; OpenFOAM;

   Sammanfattning : Cavitating multi-phase flows include an extensive range of cavity structures with different length scales, from micro bubbles to large sheet cavities that may fully cover the surface of a device. To avoid high computational expenses, incompressible transport equation models are considered a practical option for simulation of large scale cavitating flows, normally with limited representation of the small scale vapour structures. LÄS MER

3. 17. Two Problems in non-linear PDE’s with Phase Transitions

   Författare :Karl Jonsson; Henrik Shahgholian; Tomas Sjödin; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Conductivity jump; Free boundary problem; Quasilinear elliptic equation; Mathematical techniques; Nonlinear analysis; Free boundary; Free-boundary problems; Quasi-linear elliptic; Quasilinear elliptic equations; Hele-Shaw flow; non-local; implicit function theorem; Heterogeneous Multi Scale; HMM; Finite Element; FEM; FE; Mathematics; Matematik;

   Sammanfattning : This thesis is in the field of non-linear partial differential equations (PDE), focusing on problems which show some type of phase-transition. A single phase Hele-Shaw flow models a Newtoninan fluid which is being injected in the space between two narrowly separated parallel planes. LÄS MER

4. 18. Numerical study of interface dynamics and phase change

   Författare :Armin Shahmardi; Luca Brandt; Srdjan Sasic; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Teknisk mekanik; Engineering Mechanics;

   Sammanfattning : Multi-phase fluid flows are ubiquitous in natural phenomena and different industrial applications such as in food industry, the medical sector, heat exchangers, power generation systems, to name a few.  Understanding the underlining  physics of multi-phase flows  proved to be a challenging task due to presence of sophisticated dynamics, including the evolution of the interface between any pair of phases, thermodynamics and possibility of phase change, interactions between the fluid phases and a solid phase, etc. LÄS MER

5. 19. Improved modeling of ultrasonic systems : feasible for industrial applications

   Författare :Pär-Erik Martinsson; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signalbehandling; Signal Processing;

   Sammanfattning : In this thesis tree aspects of ultrasonic measurement and modelling techniques have been investigated. Namely, transducer diffraction modelling using equivalent circuits, wave propagation in multi phase flow, and wave propagation in gases. The work is relevant both from an scientific point of view and from an engineering point of view. LÄS MER

7. 20. Numerical modeling of deforming bubble transport related to cavitating hydraulic turbines

   Författare :Daniel Lörstad; Institutionen för energivetenskaper; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Gases; fluid dynamics; plasmas; Gaser; fluiddynamik; plasma; Energy research; Energiforskning; Direction Averaged Curvature DAC ; Direction Averaged Normal DAN ; Volume of Solid VOS ; Volume of Fluid VOF ; Lagrangian Particle Tracking LPT ; Large Eddy Simulation LES ; bubble; multiphase; turbulent flows; CFD; hydro-turbine;

   Sammanfattning : Cavitation is a problem in many hydroelectric power plants since it can cause adverse effects on performance and damage to nearby solid surfaces. The concerns of this thesis are the numerical aspects of flow simulations in cavitating hydraulic turbines which contain several difficulties: turbulent and complex flows, steady and moving parts of the geometry, bubble transport and cavitation development. LÄS MER