Direct numerical simulation of turbulent heat transfer in annuli: Effect of heat flux ratio

Ould-Rouiss, Meryem; Redjem-Saad, L.; Lauriat, Guy

doi:10.1016/j.ijheatfluidflow.2009.02.018

Cited by 25 publications

(7 citation statements)

References 16 publications

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“…|w h | 024602-11 is typically larger in annular geometries (close to the inner wall) than it is in channel flows; see Ref. [12,13]. Furthermore, |w h | increases more than |u h | does for increasing Prandtl numbers, according to data presented by Ref.…”

Section: Heat Fluxesmentioning

confidence: 78%

Characteristics of turbulent heat transfer in an annulus at supercritical pressure

et al. 2017

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Heat transfer to fluids at supercritical pressure is different from heat transfer at lower pressures due to strong variations of the thermophysical properties with the temperature. We present and analyze results of direct numerical simulations of heat transfer to turbulent CO 2 at 8 MPa in an annulus. Periodic streamwise conditions are imposed so that mean streamwise acceleration due to variations in the density does not occur. The inner wall of the annulus is kept at a temperature of 323 K, while the outer wall is kept at a temperature of 303 K. The pseudocritical temperature T pc = 307.7 K, which is the temperature where the thermophysical properties vary the most, can be found close to the inner wall. This work is a continuation of an earlier study, in which turbulence attenuation due to the variable thermophysical properties of a fluid at supercritical pressure was studied. In the current work, the direct effects of variations in the specific heat capacity, thermal diffusivity, density, and the molecular Prandtl number on heat transfer are investigated using different techniques. Variations in the specific heat capacity cause significant differences between the mean nondimensionalized temperature and enthalpy profiles. Compared to the enthalpy fluctuations, temperature fluctuations are enhanced in regions with low specific heat capacity and diminished in regions with a large specific heat capacity. The thermal diffusivity causes local changes to the mean enthalpy gradient, which in turn affects molecular conduction of thermal energy. The turbulent heat flux is directly affected by the density, but it is also affected by the mean molecular Prandtl number and attenuated or enhanced turbulent motions. In general, enthalpy fluctuations are enhanced in regions with a large mean molecular Prandtl number, which enhances the turbulent heat flux. While analyzing the Nusselt numbers under different conditions it is found that heat transfer deterioration or enhancement can occur without streamwise acceleration or mixed convection conditions. Finally, through a combination of a relation between the Nusselt number and the radial heat fluxes, a quadrant analysis of the turbulent heat flux, and conditional averaging of the heat flux quadrants, it is shown that heat transfer from a heated surface depends on the density and the molecular Prandtl number of both hot fluid moving away from a heated surface as well as the thermophysical properties of relatively cold fluid moving towards it.

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Section: Heat Fluxesmentioning

confidence: 78%

Characteristics of turbulent heat transfer in an annulus at supercritical pressure

et al. 2017

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“…With the increase in computational power in recent years it is now possible to perform DNS studies of annulus flows, although only at Reynolds numbers well below those that commonly occur in engineering applications. Examples include the study of Chung et al [9], who studied the effect of the radius ratio and the study of Ould-Rouiss et al [29], who studied the effect of the ratio of heat fluxes at the two walls. Annulus correlations remain a topic of current research.…”

Section: Annulus Flowsmentioning

confidence: 99%

Application of a near-wall domain decomposition method to turbulent flows with heat transfer

Jones

Utyuzhnikov

2015

Computers & Fluids

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A near-wall domain decomposition method for use in turbulence modelling is applied to the k À x SST, Spalart-Allmaras and BL-v 2 =k turbulence models. The near-wall region is excluded from the main computational mesh. This eliminates the expense of computing the solution in the viscous sub layer and reduces the total computation time.A one-dimensional boundary layer equation is used to transfer the wall boundary condition from the wall to an interface located within the flow domain. The boundary conditions imposed on the interface are of Robin type and are written in mesh-independent form. The boundary layer equation can contain source terms such as the pressure gradient or near-wall damping terms. Scalar boundary conditions can be calculated using the same formalism as the boundary conditions for the velocity.The implementation of the boundary conditions is tested on a channel flow, two heated annulus flows and a two-dimensional, asymmetric diffuser. For each case, different locations of the interface boundary are tested. The results are not sensitive to the location of the interface. Friction factors and heat transfer data calculated with the domain decomposition approach compare well to the results obtained with the fully-resolved forms of the respective turbulence models.

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“…The Direct Numerical Simulation (DNS) methods have been used to obtain accurate turbulent flow field in a pipe (e.g. Sirisup et al [17] Ge and Xu [18], Ould-Rouiss et al [19], Tamano et al [20], Zhu et al [21], Li et al [22,23]). Ge and Xu [18] developed a numerical scheme capable of extending the scope of the spectral method without solving the covariant and contravariant forms of the Navier-Stokes equations in the curvilinear coordinates.…”

Section: Introductionmentioning

confidence: 99%

A finite-element algorithm for Stokes flow through oil and gas production tubing of uniform diameter

Akanji

Chidamoio

2020

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Stokes flow of a Newtonian fluid through oil and gas production tubing of uniform diameter is studied. Using a direct simulation on computer-aided design of discretised conduits, velocity profiles with gravitational effect and pressure fields are obtained for production tubing of different inner but uniform diameter. The results obtained with this new technique are compared with the integrated form of the Hagen–Poiseuille equation (i.e., lubrication approximation) and data obtained from experimental and numerical studies for flow in vertical pipes. Good agreement is found in the creeping flow regime between the computed and measured pressure fields with a coefficient of correlation of 0.97. Further, computed velocity field was benchmarked against ANSYS Fluent; a finite element commercial software package, in a single-phase flow simulation using the axial velocity profile computed at predefined locations along the geometric domains. This method offers an improved solution approach over other existing methods both in terms of computational speed and accuracy.

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Direct numerical simulation of turbulent heat transfer in annuli: Effect of heat flux ratio

Cited by 25 publications

References 16 publications

Characteristics of turbulent heat transfer in an annulus at supercritical pressure

Characteristics of turbulent heat transfer in an annulus at supercritical pressure

Application of a near-wall domain decomposition method to turbulent flows with heat transfer

A finite-element algorithm for Stokes flow through oil and gas production tubing of uniform diameter

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