Sökning: "length-scale"

Visar resultat 6 - 10 av 138 avhandlingar innehållade ordet length-scale.

1. 6. 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

3. 7. Flow structures in solid-liquid suspensions in mixing and confined jets

   Författare :Matthias Eng; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Lomb algorithm; macro-instabilities; stirred tank; integral length scale; solid-liquid; confined jet; LDV; parcticle flow; jet instability;

   Sammanfattning : This thesis investigates the influence of solid particles on different liquid flow systems.Large-scale periodic fluctuations such as macro instability (MI) phenomena in a mixingvessel and jet flows in a confined jet were experimentally analyzed by means of LDV. Theinfluences of different sized (0.5mm-2mm) glass particles (0%vol - 6. LÄS MER

4. 8. 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. 9. Martensitic Transformations in Steels : A 3D Phase-field Study

   Författare :Hemantha Kumar Yeddu; John Ågren; Annika Borgenstam; Yunzhi Wang; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Phase-field method; Martensitic transformations; Plastic de formation; Multi-length scale modeling; Microstructure; Stress states; Steels;

   Sammanfattning : Martensite is considered to be the backbone of the high strength of many commercial steels. Martensite is formed by a rapid diffusionless phase transformation, which has been the subject of extensive research studies for more than a century. LÄS MER

7. 10. Transitional boundary layers caused by free-stream turbulence

   Författare :Shahab Shahinfar; Jens Fransson; Johan Westin; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering mechanics; Teknisk mekanik;

   Sammanfattning : The present measurement campaign on the free-stream turbulence (FST) induced boundary layer transition scenario has provided a unique set of experimental data, with potential to enhance the understanding of the eect of the free-stream turbulence characteristic length scales on the transition location and not only the turbulence intensity, which has been the focus in most previous studies. Recent investigations where the turbulence intensity has been kept essentially constant, while the integral length scale has been changed, show that the transition location is advanced for increasing length scale. LÄS MER