Immersed boundary method for the incompressible Reynolds Averaged Navier–Stokes equations

Troldborg, Niels; Sørensen, Niels N.; Zahle, Frederik

doi:10.1016/j.compfluid.2022.105340

Cited by 6 publications

(2 citation statements)

References 33 publications

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“…When solving for turbulence simulations using Reynolds averaging, the variables in the N–S equation (transfer of momentum) are often split into time average and pulsating components:…”

Section: Experiments and Methodsmentioning

confidence: 99%

CFD Simulation Investigation on the Flow Field Distribution Pattern under Different Operating Environment Pressures in a Jet Impingement-Negative Pressure Reactor

Dong,

Qiu,

Chai

2023

ACS Omega

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A jet impingement-negative pressure deamination reactor (JI-NPDR) has excellent ammonia removal efficiency. The CFD numerical simulation method based on the Euler−Euler model and the realizable k−ε turbulence model was used to investigate the effect of different negative pressures at the reactor top outlet on the distribution pattern of pressure, velocity, turbulent kinetic energy, and vortex. The results indicate that the overall water flow distribution in the reactor increases in axial cohesion with the increase in negative pressure. The scattered small eddies gradually connect to a large eddy current as a whole, and the small eddies generated in the jet area also become regular and flat with the increase of negative pressures. These findings can provide detailed information for the study of flow patterns in a jet impingement-negative pressure reactor.

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“…When solving for turbulence simulations using Reynolds averaging, the variables in the N–S equation (transfer of momentum) are often split into time average and pulsating components:…”

Section: Experiments and Methodsmentioning

confidence: 99%

CFD Simulation Investigation on the Flow Field Distribution Pattern under Different Operating Environment Pressures in a Jet Impingement-Negative Pressure Reactor

Dong,

Qiu,

Chai

2023

ACS Omega

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“…It solves the finite volume discretization of the incompressible RANS equations using a SIMPLE-like solution strategy. The EllipSys flow solver has found application in numerous studies related to the simulation of wind turbine blade-resolved flows [15,16], as well as in the analysis of 2D and 3D flows over airfoils [17,18,7,19], and shape optimization of wind turbine blade tips [20] and airfoils [21].…”

Section: Flow Solvermentioning

confidence: 99%

Stabilization of SIMPLE-like RANS solvers for computing accurate gradients using the complex-step derivative method

Dicholkar,

Lønbæk,

Zahle

et al. 2024

J. Phys.: Conf. Ser.

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The Reynolds-averaged Navier-Stokes (RANS) approach in Computational Fluid Dynamics (CFD) is increasingly vital for aerodynamic design across wind turbines, gas turbines, aircraft, and rotorcraft. Enhancing the process through CFD-based design optimization requires numerous design variables, favoring gradient-based methods for better scalability than gradient-free methods. This research uses numerical differentiation techniques, particularly the complex-step derivative method, to compute gradients. Challenges arise during aerodynamic shape optimization when unconventional shapes disrupt RANS solver assumptions, causing convergence failures. These failures undermine optimization, prompting the need to enhance solver convergence for robust optimization. The modified-Boostconv method is a residual recombination method bolstering unstable eigenvalues to stabilize convergence of iterative solvers for nonlinear systems of equations. This study extends the modified-Boostconv method to combine it with the complex-step derivative technique, creating robust optimizations via RANS-CFD with accurate gradients, even for these numerically unstable cases. The main issue encountered during the complexification of the modified-Boostconv method is how to correctly ensure that the model reduction leading to the least-squares problem satisfies the complex-step derivative method. We test whether the dot product operation involved in the model reduction should be a Hermitian or non-Hermitian inner product. The problem is first tested for a simple analytical case using the logistic equation in combination with the modified-Boostconv method. It shows that the non-Hermitian inner product should be used. This is also confirmed with a similar study using the RANS solver.

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Implicit rule for the application of the 2-parameters RANS turbulence models to solve flow problems around wind turbine rotor profiles

Ajayi¹,

Unser²,

Ojo³

2023

Cleaner Engineering and Technology

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Immersed boundary method for the incompressible Reynolds Averaged Navier–Stokes equations

Cited by 6 publications

References 33 publications

CFD Simulation Investigation on the Flow Field Distribution Pattern under Different Operating Environment Pressures in a Jet Impingement-Negative Pressure Reactor

CFD Simulation Investigation on the Flow Field Distribution Pattern under Different Operating Environment Pressures in a Jet Impingement-Negative Pressure Reactor

Stabilization of SIMPLE-like RANS solvers for computing accurate gradients using the complex-step derivative method

Implicit rule for the application of the 2-parameters RANS turbulence models to solve flow problems around wind turbine rotor profiles

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