Thermal Discreted Dipole Approximation For Near Field Radiation Heat Transfer

In recent years,with the fast development of micro-nano technology,the heat transfer problem under micro-nano scale has become a problem to be solved urgently in the micro and nano technical field.The thermal radiation at micro-nano scales is called near-field radiation.In the heat transfer problem,when the distance between objects is smaller than or equal to the characteristic wavelength of thermal radiation,the near-field radiation heat transfer caused by the photon tunneling effect and the surface polarization effect is much greater than the thermal radiation heat transfer problem in the far field.The material properties,spacing,and microstructure of the object affect the near-field radiative heat transfer between the objects.In this paper,the near-field radiative heat transfer between multi-nanoparticle systems and complex three-dimensional structures is calculated using the dipole approximation method and thermal discreted dipole approximation method,respectively,to study the effect of near-field radiative heat transfer between nanoparticles and complex structures.Factors to play a role in thermal regulation of near-field radiation.The dipole approximation method is used to calculate the radiative heat transfer between multi-nanoparticle systems.After verifying the accuracy of the dipole calculations,we use the coupling electric dipole and magnetic dipole approximation,based on the previous works,to calculate the near-field radiation heat transfer between the metal particles.The results show that the magnetic dipoles dominate the radiation heat transfer in the near-field between the metal particles.On this basis,multiple-body problems between metal particles and non-metals were calculated.The results show that since metal does not have surface plasmon resonance in the infrared region,as a result,the multi-body system of metal particles has little effect.Then,near-field radiative heat transfer between In Sb particles of anisotropic material was calculated by dipole approximation.The results show that the dielectric constant of In Sb material changes due to the applied magnetic field,so the constant magnetic field is adjusted by the direction of the applied magnetic field can effectively adjust the near-field radiation heat transfer between In Sb particles.At the same time,the magnetic field direction and the strength of the magnetic field also influence each other to regulate the near field heat radiation.Finally,considering the influence of the metal surface on the near-field radiative heat transfer between metal particles,the role of the magnetic dipole is added to the calculation,and the reflection of electromagnetic waves emitted by the magnetic dipole is considered.The results show that the effect of the metal surface on the near-field radiative heat transfer of metal particles mainly comes from the reflection of the magnetic dipole on the surface,and the effect of the non-metal Si C surface on the near-field radiative heat transfer of metal particles mainly comes from the surface phonon polarization of Si C.In the calculation of complex structures by the thermal discreted dipole approximation method,the accuracy of the thermal discreted dipole approximation method is first verified by calculating and comparing the near-field radiative heat transfer problem of the two cubes and the anisotropic material.Then more complex model was simulated based on the thermal discreted dipole approximation.The results of calculation of near-field radiative heat transfer between silica circular cylinders show that the change of structure will not affect the resonance characteristics of the material.Afterwards,the near-field radiation heat transfer between layered cylinders formed with silica and Zn O was calculated.The results show that the near-field radiation heat transfer between the cylinders can be changed by changing the thickness of Zn O and the inner and outer layers.Finally,a manybody system formed by large structures and nanoparticles.The results show that in such manybody system,the presence of large objects can enhance near-field radiation heat transfer between the nanometers.