Opposition control (OC) is a reactive flow-control approach that mitigates the near-wall fluctuations by imposing blowing and suction at wall, being opposite to off-wall observations. We carried out high-resolution large-eddy simulations investigate effects of OC on turbulent boundary layers (TBLs) over wing chord-based Reynolds number ( ${Re}_c$ ) $200 \ 000$ . Two cases were considered: flow sides NACA0012 section an angle attack $0^{\circ }$ , NACA4412 $5^{\circ These represent TBLs...

Abstract We carried out high-fidelity large-eddy simulations to investigate the effects of uniform blowing and suction on aerodynamic efficiency a NACA4412 airfoil at moderate Reynolds number based chord length incoming velocity $$Re_c=200{,}000$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>R</mml:mi> <mml:msub> <mml:mi>e</mml:mi> <mml:mi>c</mml:mi> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>200</mml:mn> <mml:mo>,</mml:mo> <mml:mn>000</mml:mn> </mml:mrow>...

An extensive parametric study of turbulent boundary-layer control on airfoils via uniform blowing or suction is presented. The applied either the pressure side several four-digit NACA-series airfoils. considered parameter variations include angle attack, Reynolds number, intensity, airfoil camber, and thickness. Two comprehensive metrics, designed to account for additional energy required by control, are introduced evaluate net aerodynamic performance enhancements. confirms previous findings...

For adverse-pressure-gradient turbulent boundary layers, the study of integral skin-friction contributions still poses significant challenges. Beyond questions related to integration boundaries and derivation procedure, which have been thoroughly investigated in literature, an important issue is how different terms should be aggregated. The nature these flows, exhibit in-homogeneity streamwise direction, usually results cancellation between several with high absolute values. We propose a...

From an energy budget perspective, the decomposition of mean friction drag in adverse-pressure-gradient turbulent boundary layers is conducted, obtaining contributions associated with dissipation, production, and convection across layer. In wall-normal distributions decomposed constituents, positions inner peaks are well scaled viscous units, whereas outer scale regardless Reynolds number pressure-gradient magnitude.

The application of drag-control strategies on canonical wall-bounded turbulence, such as periodic channel and zero- or adverse-pressure-gradient boundary layers, raises the question how to distinguish consistently origin control effects under different reference conditions. We employ RD identity (Renard &amp; Deck, J. Fluid Mech. , vol. 790 2016, pp. 339–367) decompose mean friction drag investigate uniform blowing suction applied an NACA4412 airfoil at chord Reynolds numbers $Re_c=200\,000$...

We study different flow control methods on turbulent around a NACA4412 airfoil, using resolved large-eddy simulation (LES). find that changes in total skin friction due to blowing and suction are not very sensitive pressure-gradient conditions nor the Reynolds number. However, boundary-layer thickness, intensity of wall-normal convection, fluctuations much more affected, mostly adverse-pressure-gradient conditions, as skin-friction decompositions show. Overall, we conclude it is possible...

We created a new publicly available data set of high-fidelity numerical simulations for two obstacles in tandem invested by fully resolved turbulent boundary layer. In the three configurations skimming flow, wake interference, and isolated roughness, we identify regions intense fluctuations, production transport kinetic energy, examine anisotropy-invariants map.

Controlling and influencing the rate of particle growth in spray granulators is key for consistent product quality size, while reducing energy consumption re-circulation. To this end, we have implemented a new control device to actively change fluidization topology fluidized influence local segregation areas affected by granulation, selectively growing fine fractions at will. Simulations using computational fluid dynamics coupled with discrete element method (CFD-DEM) demonstrate how...

This work is aimed at a first characterization of coherent structures in turbulent square duct flows. Coherent are defined as connected components the domain identified places where quantity interest (such Reynolds stress or vorticity) larger than prescribed non-uniform threshold. Firstly, we qualitatively discuss how percolation analysis can be used to assess effectiveness threshold function, and it affected by statistical uncertainty. Secondly, various physical quantities that expected...

The aim of the present work is to investigate role intense Reynolds shear-stress events in generation secondary flow turbulent ducts. We consider connected regions where product instantaneous fluctuations two velocity components higher than a threshold based on long-time turbulence statistics, spirit three-dimensional quadrant analysis proposed by Lozano-Durán et al. (J. Fluid Mech., vol. 694, 2012, pp. 100–130). examine both geometrical properties these structures and their contribution...

Abstract In situ visualization on high-performance computing systems allows us to analyze simulation results that would otherwise be impossible, given the size of data sets and offline post-processing execution time. We develop an in adaptor for Paraview Catalyst Nek5000, a massively parallel Fortran C code computational fluid dynamics. perform strong scalability test up 2048 cores KTH’s Beskow Cray XC40 supercomputer assess visualization’s impact Nek5000 performance. our study case,...

In the present paper, we evaluate performances of three stochastic models for particle dispersion in case a three-dimensional turbulent flow. We consider flow channel with cubic wall-mounted obstacle, and perform large-eddy simulations (LESs) including passive particles injected behind cases low strong inertial effects. also Reynolds-averaged same case, using standard turbulence models, employ two discrete implemented open-source code OpenFOAM continuous Lagrangian model proposed by Minier...

Abstract The present study considers uniform blowing in turbulent boundary layers as active flow control scheme for drag reduction on airfoils. focus lies the important question of how to quantify potential this correctly. It is demonstrated that mass injection causes body (the resulting from stresses body) differ wake survey momentum deficit an airfoil), which classically used experiments a surrogate former. This difference related layer (BLC) penalty , unavoidable portion reflects effort...

Reynolds-number effects in the adverse-pressure-gradient (APG) turbulent boundary layer (TBL) developing on suction side of a NACA4412 wing section are assessed present work. To this end, we analyze four cases at Reynolds numbers based freestream velocity and chord length ranging from Rec = 100, 000 to 1,000,000, all them with 5 degree angle attack. The results well-resolved large-eddy simulations (LESs) used characterize effect number APG TBLs subjected approximately same pressure-gradient...

The scope of the present project is to quantify effects uniform blowing and body-force damping on turbulent boundary layers subjected a non-uniform adverse-pressure-gradient distribution. To this end, well-resolved large-eddy simulations are employed describe flow around NACA4412 airfoil at moderate Reynolds number 200, 000 based freestream velocity chord length. In paper we focus conference presentation will include comparison with applied in same region. inner-scaled profiles mean selected...

Percolation analysis is a valuable tool to study the statistical properties of turbulent flows. It based on computing percolation function for derived scalar field, thereby quantifying relative volume largest connected component in superlevel set decreasing threshold. We propose novel memory-distributed parallel algorithm finely sample function. version union-find interleaved with global synchronization step each threshold sample. The efficiency this stems from fact that operations...

Abstract This preliminary study is concerned with the identification of three-dimensional coherent structures, defined as intense Reynolds-stress events, in turbulent boundary layer developing over suction side a NACA4412 airfoil at Reynolds number based on chord lenght and incoming velocity Re c = 200, 000. The scientific interest for such flows originates from non-uniform adverse pressure gradient that affects boundary-layer development. Firstly, we assess different methods to identify...

Abstract The present study considers uniform blowing in turbulent boundary layers as active flow control scheme for drag reduction on airfoils. focus lies the important question of how to quantify potential this correctly. It is demonstrated that mass injection causes body (the resulting from stresses body) differ wake survey momentum deficit an airfoil), which classically used experiments a surrogate former. This difference related layer (BLC) penalty, unavoidable portion reflects effort...

We examine the effects of three basic but effective control strategies, namely uniform blowing, suction, and body-force damping, on intense Reynolds-stress events in turbulent boundary layer (TBL) developing suction side a NACA4412 airfoil. This flow is subjected to non-uniform adverse pressure gradient (APG), which substantially modifies its turbulence statistics with respect zero-pressure-gradient (ZPG) layer, it also changes how strategies affect flow. The strong APG results that are...

This research focuses on the identification and causality analysis of coherent structures that arise in turbulent flows square rectangular ducts. Coherent are first identified from direct numerical simulation data via proper orthogonal decomposition (POD), both by using all velocity components, after separating streamwise secondary components flow. The causal relations between mode coefficients analysed pairwise-conditional Granger analysis. We also formulate a nonlinear can account for...

The wake topology developing behind a wall-mounted square cylinder in turbulent boundary layer has been investigated using high-resolution large-eddy simulation (LES). boundary-layer thickness at the obstacle location is fixed, Reynolds number based on h and incoming free-stream velocity $u_\infty$ 10,000 while aspect ratio (AR), defined as height divided by its width, ranges from 1 to 4. stresses, anisotropy-invariant maps (AIM) kinetic energy (TKE) budget are analyzed investigate influence...