Adaptive Mesh Refinement for DDES Simulation on Transonic Compressor Cascade With Unstructured Mesh

2016 ◽  
Author(s):  
Jinlan Gou ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Shock Wave ◽  
Adaptive Mesh Refinement ◽  
Unstructured Mesh ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Surface Boundary ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Shock Wave Oscillation ◽  
Wave Oscillation

There are local flow phenomena like shock wave/boundary interaction and tip leakage flow which strongly influence the compressor performance and stability. AMR (Adaptive Mesh Refinement) strategy shows attractive property for automatically refining local mesh and predicting higher local phenomenon details. This paper develops the AMR strategy for turbomachinery with unstructured mesh. Curved surface boundary matching is focused in AMR process for achieving high level simulation accuracy. The developed AMR strategy is used to improve shock wave prediction in this paper. Firstly two dimensional RANS simulation of compressor cascade L030-4 is conducted to test the AMR strategy. Refined mesh shows better shock wave details compared with the almost none shock wave structure of baseline mesh. Then quasi-3D DDES (Delayed Detached Eddy Simulation) simulation of this compressor cascade is conducted. Shock wave oscillation phenomenon is clearly shown for this cascade. Local mesh of shock wave oscillation region is automatically refined by AMR. The refined mesh predicts better shock wave details and better turbulence motion comparing to the baseline mesh.

scholarly journals Numerical Simulation Of Supersonic Compression Ramp Flow

2021 ◽  
Vol 12 (6) ◽  
pp. 812-821
Author(s):  
Ki-Hyuk Yang Et.al
Keyword(s):  
Shock Wave ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Engineering Application ◽  
Turbulence Models ◽  
Adaptive Mesh ◽  
Equation Model ◽  
Prediction Performance ◽  
Cfd Analysis ◽  
Boundary Layer Interaction

Shock wave/boundary layer interaction (SWBLI) is a highly critical problem that occurs in aircraft in transonic or supersonic flow. This study performed CFD analysis of the supersonic ramp flow of freestream Mach number 2.79. To secure reliability of the CFD analysis, adaptive mesh refinement using a gradient p sensor was used. Through this, a grid of sufficient resolution was obtained for the region of shock wave, expansion wave, and flow separation. The prediction performance of 7 turbulence models that are widely used in engineering application were compared. The baseline k–ω two-equation model showed the best prediction performance, while the SST k–ω model, which is one of the most widely used two-equation models, and the 2 Reynolds stress models showed relatively poor prediction performance. In the SWBLI problem, the use of adaptive mesh refinement made it possible to secure sufficient grid resolution; meanwhile, comparison of the prediction performance of the various turbulence models confirmed that for the SWBLI problem, the generally used turbulence model was somewhat inappropriate.

Adaptive mesh refinement method based investigation of the interaction between shock wave, boundary layer, and tip vortex in a transonic compressor

2017 ◽  
Vol 232 (4) ◽  
pp. 694-715 ◽  
Author(s):  
Jinlan Gou ◽  
Xin Yuan ◽  
Xinrong Su
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Tip Vortex ◽  
Small Scale ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Mesh Convergence

Shock wave and tip leakage are important flow features at small length scales. These flow phenomena and their interactions play important roles in the performance of modern transonic fans and compressors. In most numerical predictions of these features, mesh convergence studies are conducted using overall performance data as criteria. However, less effort is made in assessing the quality of the predicted small-scale features using a mesh that yields a fairly accurate overall performance. In this work, this problem is addressed using the adaptive mesh refinement (AMR) method, which automatically refines the local mesh and provides very high resolution for the small-scale flow feature, at much less cost compared with globally refining the mesh. An accurate and robust AMR system suitable for turbomachinery applications is developed in this work and the widely studied NASA Rotor-37 case is investigated using the current AMR method. The complex interactions between the shock wave and the boundary layer, as well as those between the shock wave and the tip vortex, are accurately captured by AMR with a very high local grid resolution, and the flow mechanisms are analyzed in detail. The baseline mesh, which is considered to be “acceptable” according to the commonly used mesh convergence study, is unable to capture the detailed interaction between the shock wave and the boundary layer. Moreover, it falsely predicts the tip leakage vortex breakdown, which is a consequence of inadequate resolution in the tip region. Current work highlights the importance of a careful check of the mesh convergence, if small-scale features are the primary concern. The AMR method developed in this work successfully captures the flow details in the transonic compressor in an automatic fashion, and has been verified to be efficient compared with the globally mesh refinement or manually mesh regeneration.

Dynamic structural analysis of connecting rod through adaptive mesh refinement for different materials

2018 ◽  
Vol 50 (04) ◽  
pp. 561-570
Author(s):  
I. A. QAZI ◽  
A. F. ABBASI ◽  
M. S. JAMALI ◽  
INTIZAR INTIZAR ◽  
A. TUNIO ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Connecting Rod ◽  
Dynamic Structural Analysis

scholarly journals Convergence and quasi-optimal cost of adaptive algorithms for nonlinear operators including iterative linearization and algebraic solver

2021 ◽  
Author(s):  
Alexander Haberl ◽  
Dirk Praetorius ◽  
Stefan Schimanko ◽  
Martin Vohralík
Keyword(s):  
Adaptive Algorithm ◽  
Adaptive Mesh Refinement ◽  
Elliptic Boundary ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Picard Iteration ◽  
Optimal Rate ◽  
Stopping Criteria ◽  
Element Discretization ◽  
Fully Adaptive

AbstractWe consider a second-order elliptic boundary value problem with strongly monotone and Lipschitz-continuous nonlinearity. We design and study its adaptive numerical approximation interconnecting a finite element discretization, the Banach–Picard linearization, and a contractive linear algebraic solver. In particular, we identify stopping criteria for the algebraic solver that on the one hand do not request an overly tight tolerance but on the other hand are sufficient for the inexact (perturbed) Banach–Picard linearization to remain contractive. Similarly, we identify suitable stopping criteria for the Banach–Picard iteration that leave an amount of linearization error that is not harmful for the residual a posteriori error estimate to steer reliably the adaptive mesh-refinement. For the resulting algorithm, we prove a contraction of the (doubly) inexact iterates after some amount of steps of mesh-refinement/linearization/algebraic solver, leading to its linear convergence. Moreover, for usual mesh-refinement rules, we also prove that the overall error decays at the optimal rate with respect to the number of elements (degrees of freedom) added with respect to the initial mesh. Finally, we prove that our fully adaptive algorithm drives the overall error down with the same optimal rate also with respect to the overall algorithmic cost expressed as the cumulated sum of the number of mesh elements over all mesh-refinement, linearization, and algebraic solver steps. Numerical experiments support these theoretical findings and illustrate the optimal overall algorithmic cost of the fully adaptive algorithm on several test cases.

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