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The relationship between pressure and leakage air flow rate is defined by the power law between the airflow rate and the pressure difference across the building envelope as follows: [16] q L =C L ∆p n. where: q L is the volumetric leakage airflow rate expressed in m 3 h −1; C L is the air leakage coefficient expressed in m 3 h −1 Pa −n
These leakage characteristics of the building envelope can then be used to calculate how much airflow will be induced through the building envelope for a given pressure difference caused by wind, temperature difference or mechanical forces. 50 Pa can be plugged into the orifice-flow equation, along with the derived building C and n values to ...
In a nozzle or other constriction, the discharge coefficient (also known as coefficient of discharge or efflux coefficient) is the ratio of the actual discharge to the ideal discharge, [1] i.e., the ratio of the mass flow rate at the discharge end of the nozzle to that of an ideal nozzle which expands an identical working fluid from the same initial conditions to the same exit pressures.
The draft (draught in British English) flow rate induced by the stack effect can be calculated with the equation presented below. [12] [13] The equation applies only to buildings where air is both inside and outside the buildings. For buildings with one or two floors, h is the height of the building and A is the flow area
Typically this equation is used to find the average T and S values near a pumping well, from drawdown data collected during an aquifer test. This is a simple form of inverse modeling, since the result ( s ) is measured in the well, r , t , and Q are observed, and values of T and S which best reproduce the measured data are put into the equation ...
For a one-ampere discharge rate, Peukert's law is often stated as = where: is the capacity at a one-ampere discharge rate, which must be expressed in ampere hours, is the actual discharge current (i.e. current drawn from a load) in amperes,
In buildings, for heat transfer analysis, the scalar function ф in equation (1) is replaced by Temperature (T), diffusion coefficient Γ is replaced by thermal conductivity k and the source term is replaced by heat generation term e or by any heat radiation source or by both (depending upon the nature of source available) and there are ...
Note: the Strickler coefficient is the reciprocal of Manning coefficient: Ks =1/ n, having dimension of L 1/3 /T and units of m 1/3 /s; it varies from 20 m 1/3 /s (rough stone and rough surface) to 80 m 1/3 /s (smooth concrete and cast iron). The discharge formula, Q = A V, can be used to rewrite Gauckler–Manning's equation by substitution for V.