Turbulent heat transfer in pipes

This research project began as a collaboration with the ISE Research Group at the UC3M, in the context of technological problems that arise in the tubes of heat receivers in Solar Power Tower (SPT) plants. The temperature difference between the heated and adiabatic walls of these tubes results in non-negligible density differences between the hot and cold sides, which modify the turbulent transport of heat and momentum inside the pipe. As a consequence, standard eddy diffusivity models for RANS simulations do not work, and a secondary flow of the second kind develops in the flow.
This project was the main focus of the PhD Thesis of A. Antoranz, and was awarded the “Premio Fundación SENER” for the best thesis in engineering during 2017.

Variable density mixing layers: non-reactive and reactive

This research is part of the Consolider-Ingenio 2010 project, SCORE (contract # CSD2010-00011), which aims at the development of advanced and sustainable combustion systems. In collaboration with the Fluid Mechanics Department of UC3M, we aim to analyze the effect that the Lewis number has on the flame temperature of turbulent diffusion flames in a canonical configuration: a turbulent mixing layer. DNS is performed using a massively parallel solver of the Navier-Stokes equations in the low-Mach number approximation, to analyze the effect that preferential diffusion has on the temperature of the flame. As a stepping stone in the project, we have also simulated and analyzed non-reactive turbulent mixing layers between streams of different densities.

Stratified flows

Stably-stratified turbulent wall flows are receiving growing interest due to their relevance in environmental engineering and geophysical applications. The atmospheric boundary layer is typically stably stratified at night while oceanic flows are almost always stably stratified. Topics of current research in these flows are, among others, the quantification of mixing, the dynamics of strongly stratified turbulence and the structure and modeling of stable boundary layers. UW and UCSD are involved in this research effort, which has been funded by the ARO (W911NF-08-1-0155).

Flow separation

The separation of a turbulent boundary layer from a gently curving surface is a process of primary concern in numerous engineering components and applications. A few examples are highly loaded aircraft wings, fuselages at high incidence or low-pressure turbine blades. In all these cases, the presence or absence of flow separation can have a decisive influence on the ability of the device to perform effectively and safely. DNS and LES are used to understand and predict these behaviors.

Related Publications

• Effects of differential diffusion on nonpremixed-flame temperature
  Almagro, Flores, Vera, Liñan, Sánchez, Williams. Proc. Comb. Inst., 37, 1757-1766 (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) 
• A numerical study of a variable-density low-speed turbulent mixing layer.
  Almagro, García-Villalba & Flores. J. Fluid Mech., 830, 596-601 (2017) 
• On the dynamics of turbulence near a free-surface
  Flores, Riley & Horner-Devine. J. Fluid Mech., 821, 248-265 (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) 
• 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) 
• 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) 
• 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) 
• 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).  

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