Search for dissertations about: "RANS"

Showing result 1 - 5 of 118 swedish dissertations containing the word RANS.

2. 1. Methodologies for RANS-LES interfaces in turbulence-resolving simulations

   Author : Sebastian Arvidson; Chalmers tekniska högskola; []
   Keywords : 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;

   Abstract : 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. READ MORE

4. 2. Development of a Free Surface Capability in a RANS Solver with Coupled Equations and Overset Grids

   Author : Michal Orych; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; free-surface; overset; RANS;

   Abstract : This thesis is a result of investigations carried out during the implementation of a free surface capturing method in a RANS solver. The work consists of two distinct parts which complement each other, and the purpose is to improve the free surface interface sharpness and to reduce numerical diffusion of the gravity waves. READ MORE

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

   Author : Sebastian Arvidson; Chalmers tekniska högskola; []
   Keywords : 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;

   Abstract : 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. READ MORE

6. 4. Efficient Full-Scale CFD for Ship Hydrodynamics

   Author : Michal Orych; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; CFD; Self-propulsion; Ship; Verification; Uncertainty; Full-scale; Validation; Seakeeping; Energy-Saving Device; Roughness; RANS;

   Abstract : An efficient numerical approach for ship hydrodynamics, involving a hybrid free-surface potential flow/RANS method, is explored. The work focuses on estimating the delivered power of ships in calm water and in waves, highlighting the benefits of full-scale simulations, particularly for ships with Energy Saving Devices. READ MORE

7. 5. Analytical and Numerical Studies of Internal Swirling Flows

   Author : Walter Gyllenram; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; turbulence; vortex; draft tube; hydro turbine; filter; RANS; LES; swirling flow;

   Abstract : Swirling flows are common in technical applications, e.g. turbines, pumps, fans, compressors and combustors. READ MORE