Sökning: "Nonlinear flow"

Visar resultat 16 - 20 av 152 avhandlingar innehållade orden Nonlinear flow.

1. 16. Realistic simulations of delta wing aerodynamics using novel CFD methods

   Författare :Stefan Görtz; Arthur Rizzi; Miguel Visbal; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; CFD; aerodynamics; flow physics; steady; unsteady; delta wing; vortical flow; Rymd- och plasmafysik; Space physics; Rymdfysik;

   Sammanfattning : The overall goal of the research presented in this thesis is to extend the physical understanding of the unsteady external aerodynamics associated with highly maneuverable delta-wing aircraft by using and developing novel, more efficient computational fluid dynamics (CFD) tools. More specific, the main purpose is to simulate and better understand the basic fluid phenomena, such as vortex breakdown, that limit the performance of delta-wing aircraft. LÄS MER

3. 17. Modelling of IC-Engine Intake Noise

   Författare :Magnus Knutsson; Mats Åbom; Yves Auregán; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; IC-engine; intake noise; gas dynamics; linear source data; frequency domain; 2-port; losses; air cleaner unit; filter paper; flow; FEM; BEM; charge air cooler; narrow tube; Acoustics; Akustik;

   Sammanfattning : Shorter product development cycles, densely packed engine compartments and intensified noiselegislation increase the need for accurate predictions of IC-engine air intake noise at earlystages. The urgent focus on the increasing CO2 emissions and the efficiency of IC-engines, aswell as new techniques such as homogeneous charge compression ignition (HCCI) mightworsen the noise situation. LÄS MER

4. 18. Rock grouting design: Rheological aspects and radial flow visualizations with ultrasound

   Författare :John Shamu; Stefan Larsson; Ulf Håkansson; Liangchao Zou; Chadi El Mohtar; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cement grouts; grouting; yield stress fluid YSF ; thixotropy; critical shear rate; radial flow; wall slip; Bingham model; Cementbaserade injekteringsmedels; injektering; icke-Newtonska vätskors; tixotropi; kritisk deformationshastigheten; radiella strömning; glidning; Bingham modell; Jord- och bergmekanik; Soil and Rock Mechanics;

   Sammanfattning : The rheological properties of cement-based grouts play a crucial role indetermining the final spread in grouted rock formations. In rheological terms,cement grouts are known to be complex time-dependent yield stress fluids,but their steady flow behavior is often described by the simple Binghamconstitutive law. LÄS MER

5. 19. Theoretical and Experimental Investigations of Nonlinear Flame Instability

   Författare :Li-Zheng Ma; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; nonlinear hydrodynamic instability; flame propagation and stretch effects; shock induced flame instability; tulip flame formation; interface tracking; the Schlieren technique; level set approach;

   Sammanfattning : Flame instability is both important and difficult to understand. Mechanisms of instability are complex, because instability often involves an interaction between several different physical phenomena, such as an unsteady chemical reaction, unsteady flame propagation generating an unsteady flow, acoustic waves or shock waves. LÄS MER

7. 20. Unsaturated Solute Transport in a Semiarid Catchment - Nonlinear Analyses and Modelling

   Författare :Pernilla Öhrström; Avdelningen för Teknisk vattenresurslära; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; teknisk geografi; Hydrogeologi; teknisk geologi; unsaturated zone; Hydrogeology; geographical and geological engineering; solute transport; scaling; soils; semiarid regions; heterogeneity; preferential flow; fractals;

   Sammanfattning : Unsaturated solute transport is highly variable and therefore difficult to predict. In semi-arid areas, where water resources are limited, the presence of macropores is of great importance for crop production. The bromide ion (Br-) and dye tracers are useful for studies of water movement. LÄS MER