The view factor F12 is best described as which of the following?

The view factor F12 is best described as which of the following?

• A. A measure of fluid drag between surfaces
• B. A factor for mixing efficiency
• C. The radiation heat transfer parameter between two surfaces
• D. The dimensionless coefficient for mass transfer

Answer: (C)

Radiation exchange between surfaces is captured by view factors, which quantify how geometry governs energy transfer by radiation. The value F12 represents the fraction of energy emitted by surface 1 that directly reaches surface 2, depending only on the shapes, orientations, and separation of the surfaces (not on material properties). It is a dimensionless quantity used in radiative heat transfer calculations, often alongside areas and emissivities to determine the net exchange. A useful relation is reciprocity: A1 times F12 equals A2 times F21, linking the view factors in both directions. This concept is not about fluid drag, mixing efficiency, or mass-transfer coefficient, which involve different transport mechanisms.

Radiation exchange between surfaces is captured by view factors, which quantify how geometry governs energy transfer by radiation. The value F12 represents the fraction of energy emitted by surface 1 that directly reaches surface 2, depending only on the shapes, orientations, and separation of the surfaces (not on material properties). It is a dimensionless quantity used in radiative heat transfer calculations, often alongside areas and emissivities to determine the net exchange. A useful relation is reciprocity: A1 times F12 equals A2 times F21, linking the view factors in both directions. This concept is not about fluid drag, mixing efficiency, or mass-transfer coefficient, which involve different transport mechanisms.