Curvature Coefficient

Curvature coefficient, abbreviated as \(C_c\), also called coefficient of curvature, a dimensionless number, classifies a soil as well graded or poorly graded.  It is a measure of the fineness or coarseness of the soil particles.  Particle size distribution curves are commonly used in geotechnical engineering to describe the distribution of different sizes of particles in a soil sample.  These curves provide information about the proportion of various particle sizes within the soil.

Curvature Coefficient Categorizes Fluids into Different Regimes

• Mildly Curved Flow (C < 1)  -  The curvature effects are relatively small, and the flow behaves similarly to that in a straight channel.
• Moderately Curved Flow (1 < C < 100)  -  The curvature starts to significantly influence the flow patterns, leading to secondary flow structures.
• Strongly Curved Flow (C > 100)  -  The curvature dominates the flow behavior, and the secondary flow patterns become even more pronounced.

Curvature Coefficient Formula
\( C_c \;=\;  \dfrac{ D_{30}^2 }{ D_{60} \cdot D_{10}   }\)     (Curvature Coefficient) \( D_{30} \;=\; \sqrt{ C_c \cdot D_{60} \cdot D_{10} }   \) \( D_{60} \;=\;   \dfrac{ D_{30}^2 }{ C_c \cdot D_{10}   }\) \( D_{10} \;=\;   \dfrac{ D_{30}^2 }{ C_c \cdot D_{60}   }\)
Symbol	English	Metric
\( C_c \) = Curvature Coefficient	\(dimensionless\)	\(dimensionless\)
\( D_{30} \) = the sieve diameter (grain size) which there are 30% of particles go through.	\(in\)	\(mm\)
\( D_{60} \) = the sieve diameter (grain size) which there are 60% of particles go through.	\(in\)	\(mm\)
\( D_{10} \) = the sieve diameter (grain size) which there are 10% of particles go through.	\(in\)	\(mm\)