Near-field radiative heat transfer between rough surfaces modeled using effective media with gradient distribution of dielectric function

Journal Article · Sat Jul 27 00:00:00 EDT 2019 · International Journal of Heat and Mass Transfer

DOI:https://doi.org/10.1016/j.ijheatmasstransfer.2019.118432· OSTI ID:1594788

Xu, D. Y. ^[1]; Bilal, A. ^[2]; Zhao, J. M. ^[3]; Liu, L. H. ^[4]; Zhang, Z. M. ^[5]

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1. Harbin Inst. of Technology (China); Georgia Institute of Technology
2. Harbin Inst. of Technology (China)
3. Harbin Inst. of Technology (China); Key Lab. of Aerospace Thermophysics, Harbin (China)
4. Harbin Inst. of Technology (China); Shandong Univ., Qingdoa (China)
5. Georgia Inst. of Technology, Atlanta, GA (United States)

Near-field radiative heat transfer (NFRHT) between rough surfaces, due to its widespread presence in engineering practice of near-field energy utilization, requires indepth studies, especially from the perspective of physical mechanism. In this paper, an effective multilayer model is built to approach the NFRHT between random rough surfaces of silicon carbide (SiC). Using the effective medium theory (EMT), the effective dielectric function of each layer is obtained, which forms a gradient distribution of dielectric function along the depth of the medium. The influence of the effective dielectric function on surface phonon polaritons (SPhPs) is analyzed, showing that the effective layers with small filling fraction of SiC feature lower SPhP resonance frequencies than SiC bulk. The coupling of SPhPs from the gradient distribution of dielectric function produces new surface modes that dominates the NFRHT. Investigation on the effect of root mean square height (RMS height, σ) reveals that the peaks of local density of states (LDOS) and spectral heat flux are red-shifted as σ increases, while the spectral heat flux below the peak frequency gets larger. This can be attributed to the coupling of SPhPs inside the rough layer. We also found the total net heat flux between rough surfaces separated by an average distance exceeds that between smooth plates and increases with increasing σ, which offer a new way to enhance NFRHT. Finally, this work provides a reference for the simulation and understanding of the NFRHT between rough surfaces.

• Research Organization: Georgia Inst. of Technology, Atlanta, GA (United States)
• Sponsoring Organization: National Natural Science Foundation of China (NNSFC); USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: SC0018369
• OSTI ID: 1594788
• Alternate ID(s): OSTI ID: 1698095
• Journal Information: International Journal of Heat and Mass Transfer, Journal Name: International Journal of Heat and Mass Transfer Journal Issue: C Vol. 142; ISSN 0017-9310
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
effective media
gradient distribution of dielectric function
near-field radiative heat transfer
rough surface