Roughness length, calculation

The theoretical concentration in air downwind of an area source as a function of the roughness length and atmospheric stability has been given by Wilson (1982). Shinn et al. found z0 = 0.02 m at the Nevada site. The dimensionless concentration u Xi/Q from (6.25) is 8.3, and this would agree with Wilson s calculations for average (neutral) stability if the fetch of wind over the source of resuspended dust was 10 km. 

Proceeding from the urban LUC, the calculation of the main aerodynamic characteristics of urban areas such as the roughness length and displacement height, can be performed based on the morphometric or morphologic methods. 

The contributions of the horizontal surfaces (canyon floor and roofs) are calculated using the formulation of Louis 1979 [379] based on the MOST. The roughness lengths used for this calculation are representative for the local roughness of the specific surface types (roofs or canyon floor) and not for the entire city, as it was considered in the first module (Section 9.3.1). 

Colder (1972) established a relation between the Pasquill stability classes, the roughness length zo and L (Figure 16.8). To simplify calculation of /L, Colder s plot can be approximated by the correlation... 

From your knowledge of the thermal-neutron diffusion length, calculate roughly the effect of the 2-ft dimension on L. Will a box 2 x 2 ft be large enough ... 

Although LHF is often a better theoretical treatment of open-shell systems than the RHF (half-electron) methods, it takes longer to compute. Separate matrices for electrons of each spin roughly double the length of the calculation. ... 

The following analysis enables one to calculate the diameter of a pipeline transporting any compressible fluid. The required inputs are volumetric flow rate, the specific gravity of the gas relative to air, flow conditions, compressibility factor Z where Z is defined by nZRT = PV, the pressure at the point of origin and the destination, the pipe length, and pipe constants such as effective roughness. The working equations have been obtained from the literature. Since the friction factor... 

The value of C3 is 0.011454 in USCS units and 20.178 x 10 in SI units. The inputs for the calculation are Q (bbl/hr or mVhr) and pipeline length (miles or km), viscosity U (Centistokes), pipe diameter D (inches or meters), effective pipe roughness e, and pipeline lengths (miles or km). The Fanning friction factor is... 

The pressure drop in a pipe, due to friction, is a function of the fluid flow-rate, fluid density and viscosity, pipe diameter, pipe surface roughness and the length of the pipe. It can be calculated using the following equation ... 

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