Sökning: "Teknisk mekanik Strömningsmekanik"

Visar resultat 21 - 25 av 136 avhandlingar innehållade orden Teknisk mekanik Strömningsmekanik.

1. 21. Development of Numerical Methods for Accurate and Efficient Scale-Resolving Simulations

   Författare :Magnus Carlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; High-order gradient reconstruction; Hybrid RANS-LES; Scale-resolving simulation; Synthetic Turbulence; Numerical methods; Turbulence modelling;

   Sammanfattning : Hybrid RANS (Reynolds-Averaged Navier-Stokes)-LES (Large-Eddy Simulation) techniques are considered to be sufficiently accurate and computationally affordable for the aeronautical industry. Scale-resolving simulations is a powerful tool that can accurately predict complex unsteady compressible high-Reynolds-number turbulent flows, as often encountered aeronautical applications. LÄS MER

3. 22. Towards Improved Scale-Resolving Modeling and Simulations of Turbulent Flows

   Författare :Magnus Carlsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Hybrid RANS-LES; Numerical methods; Synthetic Turbulence; Compressible flow; Scale-resolving simu- lation; High-order gradient reconstruction; Turbulence modelling;

   Sammanfattning : Scale-resolving simulations are viewed as powerful means for predicting complex turbulentflows, as often encountered in aeronautical applications. However, since turbulent scalesspan over a considerable range from the smallest Kolmogorov scales to the largest ofequivalence to configuration size, scale-resolving computations are often demandingon computational resources and, furthermore, on the underlying numerical methodsused in the simulations. LÄS MER

4. 23. Active Control and Reduced-Order Modeling of Transition in Shear Flows

   Författare :Reza Dadfar; Dan S. Henningson; Ardeshir Hanifi; Shervin Bagheri; Vassilis Theofilis; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SRA - E-Science SeRC ; SRA - E-vetenskap SeRC ;

   Sammanfattning : In this thesis direct numerical simulation is used to investigate the possibilityto delay the transition from laminar to turbulent in boundary layer flows.Furthermore, modal analysis is used to reveal the coherent structures in highdimensional dynamical systems arising in the flow problems. LÄS MER

5. 24. A pressure coupled Representative Interactive Linear Eddy Model (RILEM) for heavy-duty truck engine combustion simulations

   Författare :Nidal Doubiani; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Representative interactive linear eddy model; multiple LEM lines; turbulent chemistry interaction; pressure coupling; pollutants formation.;

   Sammanfattning : Internal combustion engines (ICE) are frequently debated due to their environmental consequences. Although the switch to electromobility is currently happening for light and medium-duty vessels, the transition for ships and heavy-duty trucks is more complex. The primary problem in the shift is the incapability of matching the range of ICE. LÄS MER

7. 25. Particulate Formation in GDI Engines

   Författare :Sreelekha Etikyala; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; PM; Alternate fuels; Gasoline Direct Injection; internal combustion engines; Particulate Number; Load transients;

   Sammanfattning : The need to comply with stringent emission regulations while improving fuel economy and reducing criteria pollutant emissions from transportation presents a major challenge in the design of gasoline Direct Injection (DI) engines because of the adverse effects of ultrafine Particulate Number (PN) emissions on human health and other environmental concerns. With upcoming advances in vehicle electrification, it may be the case that electric vehicles completely replace all current vehicles powered by internal combustion engines ensuring zero emissions. LÄS MER