Boltzman constant

In equation (2) Rq is the equivalent capillary radius calculated from the bed hydraulic radius (l7), Rp is the particle radius, and the exponential, fxinction contains, in addition the Boltzman constant and temperature, the total energy of interaction between the particle and capillary wall force fields. The particle streamline velocity Vp(r) contains a correction for the wall effect (l8). A similar expression for results with the exception that for the marker the van der Waals attraction and Born repulsion terms as well as the wall effect are considered to be negligible (3 ). 

As the temperature is increased, the interparticle potential kx1 2/2 becomes more and more important until a critical value Tcr V/(2tt)2 is reached (we take the Boltzman constant equal to unity), when the kinetic energy is large enough to overcome the on-site potential barrier. At this point low frequency appears and this happens at the critical temperatures Tcr = 0.13 for V = 5 (left), and Tcr = 0.025 for V = 1 (right). This is in quite good agreement with the data of Fig.8. 

Where v is the frequency of the photon, h is Plancks constant, k is Boltzmans constant and T is the temperature in Kelvin. Thus when h.v k.T stimulated emission dominates. Conversely, at high frequencies h.v k.T the spontaneous emission is most likely. A more detailed picture of the frequency and temperature dependence is presented in Figure... 

In Equation (5.8), hcom- is the convection heat transfer coefficient, A is the surface area, Ts is the solid surface temperature and Tb is the bulk fluid temperature. In Equation (5.9), F 2 is the view factor from surface 1 to 2, a is the Stefan-Boltzman constant, ei, e2 are emissivities, T, T2 are temperatures of surfaces 1 and 2 respectively. 

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