# Computational Fluid Dynamics Lab

# Computational Fluid Dynamics Lab

# CFD Lab Menu

## Research projects

## Publications

## Collaborators

## Contacts

# Other research projects

# Dynamics and Control in Aerospace Systems

# Plasma and Space Propulsion Team (EP2)

# Tethers Applied to Aerospace Engineering

# Aeroelastic and Structural Design Lab

# Experimental Aerodynamics and Propusion Lab

The research of the CFD Lab focuses on the study of fundamental phenomena in complex and/or turbulent flows. Of particular interest is the interaction of these flows with solid walls, and how these interactions result in the generation of aerodynamic forces, the mixing of different species in the fluid, and the heat transfer. These processes range from turbulent drag in commercial airplanes to the aerodynamics of small flyers, from mixing in the atmospheric boundary layer to the mixing in the human heart, and they are crucial in many engineering areas.

In the Computational Fluid Dynamics Lab we analyze these complex flows using **High Performance Computing tools** that run in massive parallel supercomputers. We are experts in developing and running Direct Numerical Simulation (DNS) and/or Large Eddy Simulation (LES) solvers.

A brief summary of the active research projects of our group can be found below, followed by our publications and a list of our collaborators. Currently, the staff of the group includes two junior researchers (S. Olivieri and A. Vela), three PhD students (J.M. Catalán, M. Guerrero and C. Martínez-Muriel) and a few bachelor and master students.

# Research Projects

Active projects developed in the CFD Lab are described below.

##### Unsteady Aerodynamics at low Reynolds numbers

There are many bio-inspired engineering devices that benefit from unique aerodynamic mechanisms that appear in low-Reynolds unsteady aerodynamics, like the maneuverability of birds and insects or the stability of the descent of winged seeds. Our work in this area aims to understand these processes in a way that enables the design of vehicles or devices that exploit them in an efficient way (i.e., flight control strategies for flapping Micro Air Vehicles). Our research is based on numerical simulations, which are performed with TUCAN: an in-house DNS solver for the Navier-Stokes equations that uses an Immersed Boundary method. Current research efforts are aimed at the analysis of flapping wings in tandem, taking into account aeroelastic and dynamic effects (i.e., the two-way coupling between the aerodynamic forces and the dynamic response of the vehicle), as well as unsteady response of airfoils to gusts.

This research is funded by the Spanish Ministry of Economy and Competitiveness, through several consecutive grants (TRA 2012-37714, TRA 2013-41103-P, DPI 2016-76151-C2-2-R), in collaboration with researchers at the Universidad de Malaga and Karlsruhe Institute of Technology.

##### Wall bounded turbulent flows

Many turbulent flows of engineering interest are bounded by solid surfaces (walls), which are responsible for the generation of friction drag, one of the main concerns of the Aerospace industry. Also, most engineering applications attempt to control turbulent flows using actuators at these surfaces. The success of these applications depend on our ability to predict the interaction between walls and turbulent eddies. The natural roughness of the surface, or the deposition of debris, complicates these interactions. In the CFD Lab., we use DNS of simple wall-bounded flows to improve our understanding of wall-bounded turbulent flows.

This research is funded by the project COTURB of the ERC, where we are collaborating with the Fluid Dynamics Group UPM and the Experimental Aerodynamics and Propulsion Lab at the UC3M. This line of research benefits from sporadic collaborations with researchers from the KTH Royal Institute of Technology in Stockholm and from the University of Washington.

##### Cardiovascular Fluid Mechanics

Cardiac diseases are one of the major health issues in developed countries. In many of these diseases, the blood flow in the heart plays a crucial role, either by transporting biochemical signals or by stressing blood cells and cardiac muscles. In such scenarios, detailed simulations of the blood flow inside the heart allow physicians and researchers to achieve a better understanding of the disease, and to develop clinical tests and treatments. In this framework, we are collaborating with physicians at the Hospital General Universitario Gregorio Marañon and engineers and physicians from the University of Washington and UC San Diego to perform patient specific simulations of the blood flow in the left heart. The objective is to develop indices that allow a personalized evaluation of the risk of stroke for the patient. This research is funded by PID2019-107279RB-I00, grant by MCIN/AEI/10.13039/501100011033/.

##### Multiphase flows

# Publications

##### PhD disertations

- Fluid-structure interaction in bioinspired locomotion problems G. Arranz Fernández, 2021.
- Aerodynamic forces and vortex structures of flapping wings in forward flight A. Gonzalo, 2018.
- Direct numerical simulation of reactive and non-reactive mixing layers: turbulent flow analysis under the Low-Mach number formulation. A. Almagro, 2017.
- A numerical study of turbulent heat transfer in pipes. A. Antoranz, 2017.
- A numerical study on the aerodynamic forces and the wake stability of flapping flight at low Reynolds number. M. Moriche, 2017.

##### Non-exhaustive list of Journal Papers

**2021**

- Characterization of aerodynamic forces on wings in plunge maneuvers. Moriche, G. Sedky, A. R. Jones, O. Flores and M. García-Villalba . AIAA J., 59(2), 736–747, 2021.
- Demonstration of patient-specific simulations to assess left atrial appendage thrombogenesis risk. García-Villalba, L. Rossini, A. Gonzalo, D. Vigneault, P. Martinez-Legazpi, E. Durán, O. Flores, J. Bermejo, E. McVeigh, A. M. Kahn, and J.C. del Alamo. Frontiers Physiol., 12, 596596, 202.
- Three-dimensional effects on plunging airfoils at low Reynolds numbers. Moriche, A. Gonzalo, O. Flores and M. García-Villalba AIAA J., 59(1), 65–74, 2021.

**2020**

- Analysis of vortical gust impact on airfoils at low Reynolds number. Martínez-Muriel, C., & Flores, O. J. Fluids and Struct., 99, 103138 (2020)
- Three-dimensional effects on the aerodynamic performance of flapping wings in tandem configuration. Arranz, Flores, & García-Villalba. J. Fluids and Struct., 94, 102893 (2020)
- Assesing aerodynamics force estimation with experiments and simulations of flapping-airfoil flows on the verge of three-dimensionality. Moriche, Raiola, DIscetti, Ianiro, Flores, & García-Villalba. Proc. Inst. Mech. Eng., Part G: J. Aero. Eng., 234, (2), 428-444 (2020)

**2018**

- From flapping to heaving: A numerical study of wings in forward flight. Gonzalo, Arranz, Moriche, García-Villalba & Flores. J. Fluids and Struct., 83, 293-309 (2018)
- A numerical study of the flow around a model winged seed in auto-rotation. Arranz, Uhlmann, Flores & García-Villalba. Flow, Turb. and Comb., 101, (2), 477-497 (2018)
- Effects of differential diffusion on nonpremixed-flame temperature. Almagro, Flores, Vera, Liñan, Sánchez, Williams. Proc. Comb. Inst., 37, 1757-1766 (2018)
- Kinematics of the auto-rotation of a model winged seed. Arranz, Moriche, Uhlmann, Flores & García-Villalba. Bioinsp. Biomim., 13, (3), 036011 (2018)
- Extended proper orthogonal decomposition of non-homogeneous thermal fields in a turbulent pipe flow.. Antoranz, Ianiro, Flores & García-Villalba. Int. J. Heat and Mass Transfer., 118, 1264-1275 (2018)

**2017**

- A numerical study of a variable-density low-speed turbulent mixing layer. Almagro, García-Villalba & Flores. J. Fluid Mech., 830, 569-601 (2017)
- On the aerodynamic forces on heaving and pitching airfoils at low Reynolds number. Moriche, Flores & García-Villalba. J. Fluid Mech., 828, 395-423 (2017)
- On the dynamics of turbulence near a free-surface. Flores, Riley & Horner-Devine. J. Fluid Mech., 821, 248-265 (2017)
- Modeling and dynamics of a two-line kite. Sánchez-Arriaga, García-Villalba & Schmehl. Appl. Math. Model., 47C, 473-486, (2017)
- Influence of the secondary motions on pollutant mixing in a meandering open channel flow.. Moncho-Esteve, Folke, García-Villalba & Palau-Salvador. Environ. Fluid Mech., 17, 695-714 (2017)

**2016**

- Three-dimensional instabilities in the wake of a flapping wing at low Reynolds number. Moriche, Flores & García-Villalba. Int. J. Heat Fluid Flow, 62, 44-55 (2016)
- Heat transfer and thermal stresses in a circular tube with a non-uniform heat flux.. Marugán-Cruz, O. Flores, D. Santana & García-Villalba. Int. J. Heat Mass TRansfer, 96, 256-266 (2016)

**2015**

- Hairpin vortices in turbulent boundary layers. Etiel-Amor, Orlu, Schlatter & Flores Phys. Fluids, 27, 2, 10.1063/1.4907783 (2015)
- Numerical simulation of heat transfer in a pipe with non-homogeneous thermal boundary conditions. Antoranz, Gonzalo, Flores & García-Villalba. Int. J. Heat and Fluid Flow, 55, 45-51 (2015)

**2014**

- Forced Convection Heat Transfer from a Finite-Height Cylinder. García-Villalba, Palau-Salvador & Rodi. Flow, Turb. and Comb., 93, 1, 171-187(2014)
- Experimental and large eddy simulation study of the flow developed by a sequence of lateral obstacles. Brevis, García-Villalba & Nińo. Env. Fluid Mech., 14, 4, 873-893 (2014)

**2013**

- Spatial and temporal scales of force and torque acting on wall-mounted spherical particles in open channel flow. Chan-Braun, García-Villalba & Uhlmann. Phys. Fluids, 25, 075103 (2013)

**2012**

- DNS of vertical plane channel flow with finite-size particles: Voronoi analysis, acceleration statistics and particle-conditioned averaging. García-Villalba, Kidanemariam & Uhlmann. Int. J. Multiphase Flow, (2012)
- The three-dimensional structure of momentum transfer in turbulent channels. Lspano-Durán, Flores & Jiménez. J Fluid Mech, doi:10.1017/jfm.2011.524 (2012)

**2011**

- Force and torque acting on particles in a transitionally rough open channel flow. Chan-Braun, García-Villalba & Uhlmann. J Fluid Mech, 684, pp 441-474, (2011)
- Turbulence modification by stable stratification in channel flow. García-Villalba & del Álamo. Phys Fluids, 23, 045104 (2011).
- Analysis of turbulence collapse in the stable stratified surface layer using Direct Numerical Simulation. Flores & Riley. Boundary-Layer Meteorol, 139 pp 241-259 (2011).

**2010**

- Hierarchy of minimal flow units in the logarithmic layer. Flores & Jiménez. Phys Fluids, 22 (7) pp 071704 (2010).

**2009**

- Large eddy simulation of separated flow over a three-dimensional axisymmetric hill. García-Villalba, Li, Rodi & Leschziner. J Fluid Mech, 627, 55-96 (2009).

**2007**

- Vorticity organization in the outer layer of turbulent channels with disturbed walls. Flores, del Álamo & Jiménez. J Fluid Mech, 591 pp 145-154 (2007).
- Effect of wall-boundary disturbances on turbulent channel flows. Flores & Jiménez. J Fluid Mech, 566 pp 357-376 (2006).

**2006**

- Identification and analysis of coherent structures in the near field of a turbulent unconfined annular swirling jet using large eddy simulation. García-Villalba, Fröhlich & Rodi. Phys Fluids, 18, 055103 (2006).

**2004**

- The large scale dynamics of near-wall turbulence. Jiménez, del Álamo & Flores. J Fluid Mech, 505 pp 179-199 (2004).

# Collaborators

##### Collaborators list

- Juan Carlos del Álamo, University of California San Diego.
- Javier Bermejo, Hospital General Universitario Gregorio Marañon.
- Wernher Brevis, Universidad Pontificia Católoca de Chile.
- Jochen Fröhlich, Technical University of Dresden.
- Manuel Garcia Villalba Navaridas, Technical University of Wien.
- Javier Jiménez, Universidad Politécnica de Madrid.
- Guillermo Palau, Universidad Politécnica de Valencia.
- James J Riley, University of Washington.
- Wolfgang Rodi, Karlsruhe Institute of Technology.
- Markus Uhlmann, Karlsruhe Institute of Technology.
- Jan Wissink, Brunel University.

# Contacts

# Óscar Flores

Vice-Dean of the Aerospace Engineering Degree

Office 7.1.H15 | Tel: +34 91 624 8217

Research Topics: CFD simulations, Fluid-Structure Interaction, Plasma Propulsion

# Other research projects