Modelling of the conjugate natural convection in a closed system with the radiant heating source radiant energy distribution by Lambert’s cosine law

Abstract

Various types of emitters are often used as energy sources in real engineering systems and technological processes. Investigations of heat transfer basic laws in such systems are of interest. We conducted mathematical modelling of conjugate heat transfer in a closed rectangular cavity under conditions of radiant energy source operating. The 2-D problem of conjugate natural convection in vorticity stream function-temperature dimensionless variables has been numerically solved by means of the finite difference method. Radiant energy distribution along the gas-wall interfaces was set by Lamberts? cosine law. We obtained fields of temperature and stream functions in a wide range of governing parameters (Rayleigh number 104 ? Ra ? 106, the length of radiant heating source 0.15 ? D ? 0.6). Then we analyzed how heat retaining properties of finite thickness heat conducting walls made of different materials affect the heat transfer intensity. Differential characteristics distribution showed significant non-uniformity and non-stationarity of the conjugate heat transfer process under study.

Pharmacodynamic Implications of Transcranial Photobiomodulation and Quantum Physics in Clinical Medicine

“…Applications of quantum mechanics to the study of light therapy interventions suggest that the cosine emission law and the inverse square law of illuminance are relevant to the pharmacodynamic processes that underlie clinical responsivity to tPBM [28,[36][37][38][39][40]. The inverse square law of illuminance states that the light received by any surface is dependent upon the distance of the targeted surface in relation to the source of light [39,40].…”

“…The inverse square law of illuminance states that the light received by any surface is dependent upon the distance of the targeted surface in relation to the source of light [39,40]. Considerations of the cosine emissions law indicate that the intensity of light covaries according to the distribution area of the light and its angle of incidence [28,[36][37][38].…”

“…Calculations of luminance and applications of PBM must consider Lambert's cosine law. Lambert's cosine law, also known as the cosine emission law, states that the intensity of light covaries according to the distribution area and its angle of incidence [28,[36][37][38]. As the power of light received by a surface depends on the cosine of the incidence angle, the power of a light source is significantly attenuated if the direction of light is applied orthogonal to the surface normal [28,[36][37][38].…”