Sökning: "Zonal flows"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Zonal flows.

  1. 1. Transport Barriers in Plasmas and Fluids

    Författare :Robert Moestam; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DNS; transport barriers; Zonal flows; L-H mode transition; turbulence simulations; drift waves; flux tube simulations; nonlinear instabilities; linear instabilities;

    Sammanfattning : In the present work different mechanisms for generation and suppression of turbulence are studied. The suppression of nonlinearly generated turbulence stabilized by temperature boundary conditions as well as turbulence generated by linear instabilities and suppressed by nonlinearly generated secondary flows are treated. LÄS MER

  3. 2. Assessment and Some Improvements of Hybrid RANS-LES Methods

    Författare :Sebastian Arvidson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; LES; hybrid RANS-LES; zonal RANS-LES; embedded LES; PDH-LRN; log-layer mismatch; LES length scale; shock boundary-layer interaction;

    Sammanfattning : Motivated by numerical analysis of a shock/boundary-layer interacting (SBLI) flow in a duct, where some typical existing hybrid RANS-LES methods become awkward to give accurate predictions of the shock-induced corner separation bubble, a new hybrid RANS-LES method, has been proposed. The model is based on a low-Reynolds-number (LRN) $k-\omega$ RANS model, which is one of the few models that are capable of giving reasonable predictions for the SBLI flow in RANS computations. LÄS MER

  4. 3. Methodologies for RANS-LES interfaces in turbulence-resolving simulations

    Författare :Sebastian Arvidson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; zonal RANS-LES; aeronautics; RANS-LES interfaces; Hybrid RANS-LES; grey-area mitigation; log-layer mismatch; embedded LES; LES length scale; LES;

    Sammanfattning : Hybrid Reynolds-Average Navier-Stokes (RANS)-Large-Eddy Simulations (LES) techniques are now seen by the aeronautical industry as the most promising turbulence-resolving approaches for complex high-Reynolds-number turbulent flows with regard to cost and accuracy. However, connecting RANS and LES simulated flows is a challenging task and needs special attention in order to increase simulation robustness and accuracy. LÄS MER

  5. 4. Drift Waves in General Toroidal Equilibria

    Författare :Johan Anderson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; fusion plasmas; instabilities; toroidal geometry; drift waves;

    Sammanfattning : One of the main concerns in fusion research is to understand the anomalously high transport in magnetically confined plasmas. In recent years, substantial progress in the understanding of transport in terms of drift waves in fusion plasmas has been achieved. LÄS MER

  7. 5. Atmospheric & Oceanic Applications of Eulerian and Lagrangian Transport Modelling

    Författare :Joakim Kjellsson; Kristofer Döös; Jonas Nycander; Joseph LaCasce; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Eulerian; Lagrangian; trajectory; climate; atmosphere; ocean; modelling; drifter; thermodynamic; climate change; atmosfärvetenskap och oceanografi; Atmospheric Sciences and Oceanography;

    Sammanfattning : This thesis presents several ways to understand transports of air and water masses in the atmosphere and ocean, and the transports of energy that they imply. It presents work using various kinds of observations as well as computer simulations of the atmosphere and oceans. LÄS MER