Section Factor with Respect to Surface Roughness
- August 12, 2018
- Posted by: RSIS
- Categories: Civil Engineering, Mathematics
International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue VIII, August 2018 | ISSN 2321–2705
Section Factor with Respect to Surface Roughness
Dr. Birendra Kumar Singh
Civil Engineering Department, Birla Institute of Technology, Mesra, Ranchi-835215 (Jharkhand), India
Abstract:-The relationship for section factor A2/3 with different roughness coefficient are established and the section factor is determined with respect to the derived equations with respect to maximum mean depth of flow and minimum velocity of flow. We find that the value of section factor is more with respect to maximum depth of flow as compared to minimum depth of flow because section factor depends upon mean depth of flow. As we have more mean depth of flow, it indicates more discharge of flow. Hence, section factor is more but we get less mean depth of flow with respect to minimum velocity of flow.
Keywords: Section factor; Manning’s roughness constant; Conveyance; Darcy Weisbach resistance coefficient; Constant varying with bed material properties; Flow cross sectional area; Hydraulic radius.
I. INTRODUCTION
The section factor obtained with respect to Darcy Weisbach resistance coefficient gives more value of section factor as compared to Manning’s roughness coefficient because power of mean velocity of flow is two which is in denominator and power of mean velocity of flow is unity
since f= 8gRs/V2 and n=1.49R2/3S1/2/V.
Hence there is more reduction in mean velocity of flow due to Darcy Weisbach resistance coefficient as compared to Manning’s roughness coefficient. And there will be more increase in mean depth of flow for Darcy Weisbach resistance coefficient as compared to Manning’s roughness coefficient. F =Darcy Weisbach resistance coefficient. n= Manning’s roughness coefficient. g=Acceleration due to gravity in m/sec2. R=Hydraulic radius in metre. V=Mean velocity of flow in m/sec. S=Channel slope.
The relationship between hydraulic radius and mean depth of flow is established with coefficient and power. And it is seen that as hydraulic radius increases, power which is constant, decreases.
Hence power i.e. constant which acts like surface roughness. The relationship with section factor and constant and conveyance is established and analysis is made with respect to maximum mean depth of flow and minimum velocity of flow.
