A novel model for macroscopic simulation of oscillating heat and fluid flow in porous media

Meglio, Armando Di; Massarotti, Nicola; Dragonetti, Raffaele

doi:10.1016/j.ijthermalsci.2022.107758

Cited by 12 publications

(10 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Nusselt number, as well as the permeability, slightly depends on the x-coordinate because the viscous and thermal penetration depths change with mean density/temperature. The complex permeability and Nusselt number, calculated as shown in previous work [5] and used in the macroscopic equations, are pictured in the following Figure 4. The results confirm that such a macroscopic model is suitable for modelling the thermoacoustic instability in a SWTAE, as proved by the comparison with microscopic results.…”

Section: Resultsmentioning

confidence: 99%

“…In this work, a macroscopic porous media model, derived from a previous article in case of isothermal case [4] and extended in subsequent work [5], has been applied for the first time to the stack of a SWTAE. The second section briefly reviews the governing equations of the "microscale" and "macroscale", and the third one describes the numerical setup employed in this work.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Application of the porous media approach to a Standing Wave Thermoacoustic Engine for CFD simulations

Meglio

Massarotti

2023

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

In this article, an application of the macroscopic porous media approach, suitable for CFD simulations in oscillating flows, is proposed for a simplified Standing Wave Thermo-Acoustic Engine (SWTAE), composed of a hot buffer tube, a stack - where the energy conversion takes place - and the rest of the resonator. While for a Travelling Wave Thermo-Acoustic Engine (TWTAE) a macroscopic model for porous media has been successfully applied to both regenerators (similar to the stack in a SWTA) and heat exchangers, for SWTAE this is not true. The results illustrate that a Local-Thermal Non-Equilibrium model is required to start up the SWTAE, otherwise (with the Local Thermal Equilibrium model) the thermoacoustic instability cannot arise. Furthermore, the comparison between the simulation conducted at the microscopic scale and that one at the macroscopic level, depicts that a purely Darcy-linear model employed for the macroscopic model, characterized for oscillating flows, overpredicts the pressure amplitude at periodic steady-state. For this reason, a Forchheimer-like coefficient needs to be implemented to fit the macroscopic solution with the microscopic one.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of the porous media approach to a Standing Wave Thermoacoustic Engine for CFD simulations

Meglio

Massarotti

2023

J. Phys.: Conf. Ser.

Self Cite

View full text Add to dashboard Cite

show abstract

“…This approach has demonstrated the best agreement with analytical solutions, but it requires prior numerical simulations at the pore scale to be practically implemented (Bhatti and Öztop, 2022). According to the latest extension to the method, presented by Di Meglio et al (2022), the concept of the complex permeability trueκ˜c, in terms of its real and imaginary part, can be useful to separate the viscous effect, in which the pressure gradient is time-phased with velocity, and the oscillating inertial effects in which the pressure gradient is 90° out of phase with velocity by definition. The time-domain linear macroscopic governing equation, limited to the porous media zone, is the following, as demonstrated in a previous work (Di Meglio et al , 2022): …”

Section: Governing Equationsmentioning

confidence: 99%

“…where δv=2ν/ω is the viscous penetration depth ( v is the kinematic viscosity) and ℜ(ℑ) represents the real (imaginary) part operator. The complex permeability for a parallel plate stack is (Di Meglio et al , 2022): …”

Section: Governing Equationsmentioning

confidence: 99%

“…Zhu et al (2014) proposed a numerical calculation, via direct numerical simulations, to determine the virtual mass coefficient by scaling a kinetic energy equation. The third method is the one proposed by Di Meglio et al (2022) to analytically close this problem, without performing prior simulations at the microscopic level, by linking the real and imaginary part of Johnson’s complex permeability to the classical steady-state source term and the virtual mass correction, respectively.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of non-linear losses in a parallel plate thermoacoustic stack

Di Meglio,

Massarotti,

Rolland

et al. 2023

HFF

Self Cite

View full text Add to dashboard Cite

Purpose This study aims to analyse the non-linear losses of a porous media (stack) composed by parallel plates and inserted in a resonator tube in oscillatory flows by proposing numerical correlations between pressure gradient and velocity. Design/methodology/approach The numerical correlations origin from computational fluid dynamics simulations, conducted at the microscopic scale, in which three fluid channels representing the porous media are taken into account. More specifically, for a specific frequency and stack porosity, the oscillating pressure input is varied, and the velocity and the pressure-drop are post-processed in the frequency domain (Fast Fourier Transform analysis). Findings It emerges that the viscous component of pressure drop follows a quadratic trend with respect to velocity inside the stack, while the inertial component is linear also at high-velocity regimes. Furthermore, the non-linear coefficient b of the correlation ax + bx2 (related to the Forchheimer coefficient) is discovered to be dependent on frequency. The largest value of the b is found at low frequencies as the fluid particle displacement is comparable to the stack length. Furthermore, the lower the porosity the higher the Forchheimer term because the velocity gradients at the stack geometrical discontinuities are more pronounced. Originality/value The main novelty of this work is that, for the first time, non-linear losses of a parallel plate stack are investigated from a macroscopic point of view and summarised into a non-linear correlation, similar to the steady-state and well-known Darcy–Forchheimer law. The main difference is that it considers the frequency dependence of both Darcy and Forchheimer terms. The results can be used to enhance the analysis and design of thermoacoustic devices, which use the kind of stacks studied in the present work.

show abstract

Viscoelastic effects on the oscillatory flow in a fluid‐saturated porous layer

Raghunatha,

Inc,

Vinod

2023

Heat Trans

View full text Add to dashboard Cite

The oscillating flow of the viscoelastic fluid‐saturated porous layer has been useful in many areas, including the petroleum, chemical, and bioengineering industries. It is studied using the modified Darcy‐Oldroyd‐B model in this article. The exact solution is obtained utilizing a simpler and more reasonable method. According to this velocity solution, the time‐velocity profile of one kind of viscoelastic fluid is analyzed. From the analysis, it was found that the flow behaves like the Newton fluid when the oscillating frequency is low, and the flow reversal occurs when the oscillating frequency is high. Further, velocity, temperature, shear stress, and the rate of heat transfer are exponential solutions that are obtained and analyzed for different values of known physical parameters. Finally, we recognize that the relaxation and retardation parameters in this model act in the opposite manner.

show abstract

A novel model for macroscopic simulation of oscillating heat and fluid flow in porous media

Cited by 12 publications

References 34 publications

Application of the porous media approach to a Standing Wave Thermoacoustic Engine for CFD simulations

Application of the porous media approach to a Standing Wave Thermoacoustic Engine for CFD simulations

Analysis of non-linear losses in a parallel plate thermoacoustic stack

Viscoelastic effects on the oscillatory flow in a fluid‐saturated porous layer

Contact Info

Product

Resources

About