Xesús Nogueira

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• Professor
• Professor at Universidade da Coruña

In this work, the design of a three‐legged jacket is presented, taking into account the susceptibility to the directionality of the loads in comparison with a four‐legged jacket. For this purpose, two jackets with different orientations with respect to the incoming environmental loads were modelled: the G30, which has two legs facing the main incom...

In this study, we numerically investigate the effects of the nonlinearity in the equation of state on the structure of fingers and the transport mechanisms of salt and heat in double-diffusive finger convection, utilizing the finite volume approach with high-accuracy schemes to solve the two-dimensional Navier–Stokes equations. Our system is charac...

We consider the moving least squares method to solve compressible two-phase water-water vapor flow with surface tension. A diffuse interface model based on the Navier-Stokes-Korteweg equations is coupled with a suitable system of state equations that allows for a more realistic estimation of the pressure jump across the liquid-vapor interface as a...

Given the small wavelengths and wide range of frequencies of the acoustic waves involved in Aeroacoustics problems, the use of very accurate, low-dissipative numerical schemes is the only valid option to accurately capture these phenomena. However, as the order of the scheme increases, the computational time also increases. In this work, we propose...

Mesh-based and particle methods were conceived as two different discretization strategies to solve partial differential equations. In the last two decades computational methods have diversified and a myriad of hybrid formulations that combine elements of these two approaches have been developed to solve Computational fluid dynamics problems. In thi...

We propose two techniques for computing the energy spectra for 3D unstructured meshes that are consistent across different element types. These techniques can be particularly useful when assessing the dissipation characteristics and the suitability of several popular non-linear high-order methods for implicit large-eddy simulations (iLES). Numerica...

In this paper we propose a new arbitrary-order Finite Volume method for the numerical solution of the Euler and Navier-Stokes equations on unstructured grids. Arbitrary order is achieved using a modified Moving Least Squares reconstruction, which preserves the mean values of the conservative variables. Hence, the proposed scheme changes the traditi...

UCNS3D is an open-source computational solver for compressible flows on unstructured meshes. State-of-the-art high-order methods and their associated benefits can now be implemented for industrial-scale CFD problems due to the flexibility and highly-automated generation offered by unstructured meshes. We present the governing equations of the physi...

In this work we present a high-accurate discretization to solve the compressible Navier-Stokes equations using an Arbitrary Lagrangian-Eulerian meshless method (SPH-MLS), which can be seen as a general formulation that includes some well-known meshfree methods as a particular case. The formulation is based on the use of Moving Least Squares (MLS) a...

In this work, a new discretization of the source term of the shallow water equations with non-flat bottom geometry is proposed to obtain a well-balanced scheme. A Smoothed Particle Hydrodynamics Arbitrary Lagrangian-Eulerian formulation based on Riemann solvers is presented to solve the SWE. Moving-Least Squares approximations are used to compute h...

A highly accurate SPH method with a new stabilization paradigm has been introduced by the authors in a recent paper aimed to solve Euler equations for ideal gases. We present here the extension of the method to viscous incompressible flow. Incompressibility is tackled assuming a weakly compressible approach. The method adopts the SPH-ALE framework...

In this work we present a δ-Smoothed Particle Hydrodynamics (SPH) scheme for weakly compressible flows with automatic adaptive numerical dissipation. The resulting scheme is a meshless self-adaptive method, in which the introduced artificial dissipation is designed to increase the dissipation in zones where the flow is under-resolved by the numeric...

This work deals with sound generation and transmission in a fan stage. The study is done on a subsonic Fan stage and interaction noise between the fan wakes and the Outlet Guide Vanes (OGV) is considered. For this purpose, the Linearized Euler Equations (LEE) are solved with a steady axisymmetric flow. The acoustic sources are modelled by a scatter...

In this paper, we propose a novel modification to the WENO-family schemes to reduce its intrinsic dissipation. In this work, we focus on the WENO5 scheme, which is rewritten in terms of a central plus a dissipative part, and then, the dissipation is controlled based on the flow physics. This is achieved by using the automatic dissipation adjustment...

In this paper, we propose a novel modification to the WENO-family schemes to reduce its intrinsic dissipation. In this work, we focus on the WENO5 scheme, which is rewritten in terms of a central plus a dissipative part, and then, the dissipation is controlled based on the flow physics. This is achieved by using the automatic dissipation adjustment...

In this paper a relaxed formulation of the a posteriori Multi-dimensional Optimal Order Detection (MOOD) limiting approach is introduced for weighted essentially non-oscillatory (WENO) finite volume schemes on unstructured meshes. The main goal is to minimise the computational footprint of the MOOD limiting approach by employing WENO schemes—by vir...

A new very high-order technique for solving conservation laws with curved boundary domains is proposed. A Finite Difference scheme on Cartesian grids is coupled with an original ghost cell method that provide accurate approximations for smooth solutions. The technology is based on a specific least square method with restrictions that enables to han...

In this work we present an a posteriori high-order finite volume scheme for the computation of compressible turbulent flows. An automatic dissipation adjustment (ADA) method is combined with the a posteriori paradigm, in order to obtain an implicit subgrid scale model and preserve the stability of the numerical method. Thus, the numerical scheme is...

In this work we present an a posteriori high-order finite volume scheme for the computation of compressible turbulent flows. An automatic dissipation adjustment (ADA) method is combined with the a posteriori paradigm, in order to obtain an implicit subgrid scale model and preserve the stability of the numerical method. Thus, the numerical scheme is...

The accurate predictions of the ORC expander performance rely on validated numerical tools that take into account the full complexity of the underlying physics. The expansion of organic vapor in turbomachines rotor and stator features non-ideal gas behavior with chocked flow in transonic conditions and supersonic expansion. In this paper, a finite...

In this work we solve the Navier-Stokes-Korteweg (NSK) equations to simulate a two-phase fluid with phase change. We use these equations on a diffuse interface approach, where the properties of the fluid vary continuously across the interface that separates the different phases. The model is able to describe the behavior of both phases with the sam...

In this work, we employ the Navier–Stokes–Korteweg system of equations for the simulation of phase transition flows. This system belongs to the diffuse interface models, in which both phases are separated by a non-zero thickness interface where the properties vary continuously. The key idea of these methods is the ability to use the same set of equ...

The Chimera/overset approach is widely used in the numerical simulation of flows involving moving bodies. In this approach, first used by Steger et al. in 1983, the domain is subdivided into a set of overlapping grids, which provide flexible grid adaptation, the ability to handle complex geometries and the relative motion of bodies in dynamic simul...

In this work we present a framework for a high-order hybrid method made up of an explicit finite-difference scheme and a member of the Weighted Essentially Non-Oscillatory (WENO) family. A new a posteriori switching criterion is developed based on the Multidimensional Optimal Order Detection (MOOD) method. The schemes tested here are chosen to illu...

In this work, a weakly compressible smoothed particle hydrodynamics (WCSPH) multiphase model is developed. The model is able to deal with soil-water interactions coupled in a strong and natural form. A Regularized Bingham Plastic constitutive law including a pressure-dependent Mohr Coulomb yield criterion (RBPMC- α μ ) is proposed to model fluids,...

In this work, we propose a new meshless approach based on a Galerkin discretization of a set of conservation equations on an Arbitrary Lagrangian Eulerian framework. In particular, we solve the Linearized Euler Equations, using Moving Least Squares as weight functions in the Galerkin discretization. Riemann solvers are introduced in the formulation...

In this work, a consistent Smoothed Particle Hydrodynamics (SPH) model is proposed to deal with interfacial multiphase fluid flows simulation. A Continuum Stress Surface formulation (CSS) [1] was developed in the framework of SPH method using a non-conservative first order consistency operator to calculate the divergence of stress surface tensor. T...

A high-order hybrid method consisting of a high-accurate explicit finite-difference scheme and a Weighted Essentially Non-Oscillatory (WENO) scheme is proposed in this article. Following this premise, two variants are outlined: a hybrid made up of a Finite Difference scheme and a compact WENO scheme (CRWENO 5), and a hybrid made up of a Finite Diff...

In this work a higher-order accurate finite volume method for the resolution of the Euler/Navier-Stokes equations using Chimera grid techniques is presented. The formulation is based on the use of Moving Least Squares (MLS) approximations in order to obtain higher-order accurate reconstruction and connectivity between the overlapped grids. The accu...

The representation of geometries as buildings, flood barriers or dikes in free surface flow models implies tedious and time-consuming operations in order to define accurately the shape of these objects when using a body fitted numerical mesh. The immersed boundary method is an alternative way to define solid bodies inside the computational domain w...

We present a new high-accurate, stable and low-dissipative Smooth Particle Hydrodynamics (SPH) method based on Riemann solvers. The method derives from the SPH-ALE formulation first proposed by Vila and Ben Moussa. Moving Least Squares approximations are used for the reconstruction of the variables and the computation of Taylor expansions. The stab...

In this paper we present a high-order density-based finite-volume framework for all-speed flows. The formulation is based on high-order variable reconstructions performed using Moving Least Squares approximations. In particular, we show that combining high-order discretization schemes with low-Mach fixes, it is possible to remove the grid dependenc...

This paper presents a new sliding mesh technique for the computation of unsteady viscous flows in the presence of rotating bodies. The compressible Euler and incompressible Navier-Stokes equations are solved using a higher-order (> 2) finite volume method on unstructured grids. A sliding mesh approach is employed at the interface between computatio...

A high accurate finite volume method based on the use of Moving Least Squares (MLS) approximants is presented for the resolution of the incompressible Navier–Stokes equations on unstructured grids. Moreover, in order to eliminate the decoupling between pressure and velocity, we present a new Momentum Interpolation Method that allows interpolations...

The aeroacoustic analogy is the hybrid technique most used to predict acoustic noise of open rotor turbo-machines. However it is not appropriate to turbo-machines operating in confined spaces-where the diffractions, reflections and near-field flow effects can not be neglected. To overcome this issue, acoustic sources are propagated using linearized...

A comprehensive model for the fatigue analysis of flexible pavements that considers the effects of dynamic axle loads is presented in this paper. The main objective of this work is to quantify the reduction in the structural service life of the pavement resulting from the rise of the dynamic axle loads exerted by traffic as the progressive deterior...

Finite Volume Methods were successfully used in the last years to solve differential hyperbolic problems (Leveque, Finite-volume methods for hyperbolic problems. Cambridge University Press, Cambridge, 2005). Our research is focused here on the use of the Moving Least Squares (MLS) approximations for the development of a selective limiting technique...

The sliding mesh approach is widely used in numerical simulation of turbomachinery flows to take in to account the rotor/stator or rotor/rotor interaction. This technique allows relative sliding of one grid adjacent to another grid (static or in motion). However, when a high-order method is used, the interpolation used in the sliding mesh model nee...

In this work a new higher-order (>>2) accurate finite volume method for the resolution of the incompressible Navier–Stokes equations on unstructured grids is presented. The formulation is based on the use of Moving Least Squares (MLS) approximants. Third and fourth order accurate discretizations of the convective and viscous fluxes are obtained on...

This paper describes numerical simulation and matching experimental results for oscillatory flow within a baffled tube containing tri-orifice baffles. The numerical simulation implemented a non-standard approach based on Implicit Large Eddy Simulation (ILES) to predict the flow in a situation where complex eddy formation occurs due to periodic sepa...

This paper proposes an investigation of some important properties of a high-order finite-volume moving least-squares based method (FV-MLSs) for the solution of two-dimensional Euler and Navier–Stokes equations on unstructured grids. A particular attention is paid to the computation of derivatives of shape functions by means of diffuse or full discr...

This paper describes the development of a high-order finite volume method for the solution of compressible viscous flows on unstructured meshes. The novelty of this approach is based on the use of moving Kriging shape functions for the computation of the derivatives in the numerical flux reconstruction step at the cell faces. For each cell, the suc...

The Swift–Hohenberg equation is a central nonlinear model in modern physics. Originally derived to describe the onset and evolution of roll patterns in Rayleigh–Bénard convection, it has also been applied to study a variety of complex fluids and biological materials, including neural tissues. The Swift–Hohenberg equation may be derived from a Lyapu...

The phase field crystal equation has been recently put forward as a model for microstructure evolution of two-phase systems on atomic length and diffusive time scales. The theory is cast in terms of an evolutive nonlinear sixth-order partial differential equation for the interatomic density that locally minimizes an energy functional with the const...

On a regular basis, engineering analysis requires stating and solving systems of partial differential equations (PDEs). The most powerful and widely extended techniques for solving PDEs are the so-called Weighted Residuals Methods. To this group belong, among others, the Finite ElementMethod (FEM), the Boundary Element Method (BEM), the Finite Volu...

Most of the research and development work done until now in earthing analysis is devoted to cases where the soil can be modelled in terms of an homogeneous and isotropic semi-infinite continuous medium, being the soil resistivity an order of magnitude higher than the resistivity of the electrode itself. Furthermore, all formulations of this classic...

In this paper we present TOTBEM: a freeware application for the in-house computer aided design and analysis of grounding grids. The actual version of the software is available for testing purposes (and also use) at no cost and can be run on any basic personal computer (as of 2011) with no special requirements. The distribution kit consists in a sin...

In this paper we focus on the application of a higher-order finite volume method for the resolution of Computational Aeroacoustics problems. In particular, we present the application of a finite volume method based in Moving Least Squares approximations in the context of a hybrid approach for low Mach number flows. In this case, the acoustic and ae...

In this work we present a modification of the pressure discretization for low-Mach numerical schemes. We propose using Moving-Least Squares (MLS) approximations to the discretization of the pressure flux for the numerical schemes developed for low-Mach number flows. This simple modification avoids all the problems related with checkerboard and it o...

During the last decades, research efforts are headed to develop high order methods on CFD and CAA to reach most industrial applications (complex geometries) which need, in most cases, unstructured grids. Today, higher-order methods dealing with unstructured grids remain in infancy state and they are still far from the maturity of structured grids-b...

Computational fluid dynamics (CFD) has become increasingly used in the industry for the simulation of flows. Nevertheless, the complex configurations of real engineering problems make the application of very accurate methods that only work on structured grids difficult. From this point of view, the development of higher-order methods for unstructur...

This paper presents a shock detection technique based on Moving Least Squares reproducing kernel approximations. The multiresolution properties of these kinds of approximations allow us to define a wavelet function to act as a smoothness indicator. This MLS sensor is used to detect the shock waves. When the MLS sensor is used in a finite volume fra...

In this contribution we present the application of a numerical method based on a mesh free interpolation technique (Moving Least-Squares (MLS)) in a finite volume framework to the computation of turbulent flows. Our approach is based on the monotonically implicit Large Eddy Simulation (MILES). The main idea of MILES methodology is the absence of an...

To reach most industrial applications and then complex geometries, research efforts are headed in recent years to develop high order methods on CFD and CAA, which need in most cases unstructured grids. Among others, the finite volume method seems to be a good candidate because of its ease of implementation and its adaptation for complex geometries,...

This paper is devoted to the numerical simulation of the Navier–Stokes–Korteweg equations, a phase-field model for water/water-vapor two-phase flows. We develop a numerical formulation based on isogeometric analysis that permits straightforward treatment of the higher-order partial–differential operator that represents capillarity. We introduce a n...

In this work we study the dispersion and dissipation characteristics of a higher-order finite volume method based on Moving Least Squares approximations (FV-MLS), and we analyze the influence of the kernel parameters on the properties of the scheme. Several numerical examples are included. The results clearly show a significant improvement of dispe...

In this paper it is presented the application of a higher-order finite volume method based on Moving Least Squares approximations (FV-MLS) to the resolution of non-wall-bounded compressible turbulent flows. Our approach is based on the monotonically implicit Large Eddy Simulation (MILES). The main idea of MILES methodology is the absence of any exp...

In this work we show a numerical methodology for the resolution of compressible flows in both, structured and unstructured grids. The Moving Least Squares method (MLS) is used for the computation of the gradients and successive derivatives in a higher-order finite volume framework. Using the multiresolution properties of the MLS methodology, we def...

This paper presents a comparison between two high-order methods. The first one is a high-order finite volume (FV) discretization on unstructured grids that uses a meshfree method (moving least squares (MLS)) in order to construct a piecewise polynomial reconstruction and evaluate the viscous fluxes. The second method is a discontinuous Galerkin (DG...

This paper presents the application of a high-order finite volume scheme based on the Moving Least Squares approximations (FVMLS) to solve Linearized Euler Equations (EEL) on unstructured grids. The proposed method allows the direct reconstruction of the (convective) fluxes using compact stencils, and without introducing new degrees of freedom, whi...

In this contribution we describe a numerical method based on the application of a mesh free interpolation technique (Moving Least Squares (MLS)) for the development of a higher-order finite volume discretization useful on structured and unstructured grids. With this procedure it is possible to build a higher-order scheme in which the computation of...

This paper explores the approximation power of Moving Least-Squares (MLS) approximations in the context of higher-order finite volume schemes on unstructured grids. The scope of the application of MLS is threefold: (1) computation of high-order derivatives of the field variables for a Godunov-type approach to hyperbolic problems or terms of hyperbo...