scholarly journals Radiative Heat Transfer Analysis within Three-Dimensional Clouds Subjected to Solar and Sky Irradiation

2004 ◽  
Vol 61 (24) ◽  
pp. 3125-3133 ◽  
Author(s):  
Toru Nishikawa ◽  
Shigenao Maruyama ◽  
Seigo Sakai
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Three Dimensional ◽  
Anisotropic Scattering ◽  
Heat Transfer Analysis ◽  
Radiative Cooling ◽  
Emission Model ◽  
Fair Weather ◽  
Convex Shape

Abstract A three-dimensional radiative heat transfer analysis of an arbitrary-shaped modeled cloud subjected to solar and sky irradiation has been performed. The Radiation Element Method by Ray Emission Model (REM2) was used for numerical simulation. Nongray, anisotropic scattering, absorbing, and emitting are taken into account in calculating the three-dimensional cloud. The modeled cloud is considered to be a low-level fair-weather cumulus in a tropical atmosphere. The cloud is modeled by unstructured mesh elements in order to investigate the curvature of cloud shape. Radiative cooling occurs in the thin layer below the cloud surface, and the thickness is approximately 20–40 m. Radiative cooling is enhanced at the swelled top of the cloud with a convex shape, which can cause a downward forcing and enhance the entrainment instability. On the other hand, radiative cooling close to the root of the swelled top is relatively weak. The solar heating does not affect the temperature change in the cloud compared with radiative heat transfer by longwave infrared radiation.

Radiative Heat Transfer Using Isotropic Scaling Approximation: Application to Fibrous Medium

2005 ◽  
Vol 127 (10) ◽  
pp. 1115-1123 ◽  
Author(s):  
Hervé Thierry Kamdem Tagne ◽  
Dominique Doermann Baillis
Keyword(s):  
Heat Transfer ◽  
Exact Solution ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Scattering Problem ◽  
Incident Radiation ◽  
Anisotropic Scattering ◽  
Radiative Properties ◽  
Heat Transfer Analysis ◽  
Fibrous Medium

The applicability of the isotropic scaling approximation to heat transfer analysis in fibrous medium is discussed. The isotropic scaling model allows the transformation of an anisotropic scattering problem to an isotropic one. The scaled parameters are derived for general anisotropic scattering and for radiative properties dependent of the incidence radiation. Three different isotropic scaling approaches are considered: Directional isotropic scaling, mean isotropic scaling, and P1 isotropic scaling; corresponding to isotropic scaling parameters function of incident radiation, arithmetic mean over all incident direction of radiative properties, and mean on weighted radiative properties, respectively. The discrete ordinate method is used to solve the radiative transfer equation through fibrous medium. The fibers in the medium are randomly oriented either in space or parallel to the boundaries. Numerical results presented for a pure radiation problem show good accuracy on radiative heat flux between the exact solution and solution obtained with both P1 and directional isotropic scaling while using mean isotropic scaling is unsuitable. Using isotropic scaling approximation to model radiative heat transfer is faster than the exact solution and required few quadratures to converge.

Sign in / Sign up

Export Citation Format

Share Document