CFD Study and Investigation of the Critical Ratio for Pressure-Head Ratio inside Drainage Manholes

Abstract

The objective of this research is to study the pressure-head rising inside manhole in pipelines, in relationship with the ratio from manhole diameters to its pipes diameters. The research team adopted CFD to simulate the manhole flows, at different conditions of varying inlet and outlet pipes diameter and manhole diameters. The risk of manhole overflow can also be reduced by controlling how fast is the rate of pressure-head rise per given flow rate. To reduce the peak and rate of rising of pressure-head column inside the manhole to be attained, the ratio between manhole widths (diameter) to its pipe diameter should be taken into considerations. Based on CFD analysis it is found that, ratios less than 3 are shown to have better results, producing lower peak values of pressure-head to be attained inside manholes.

Experimental and Numerical Determination of Head Loss Coefficients of Two-Way Surcharged Manholes

“…The determination of free-surface location is a part of the solution in the Volume of Fluid (VOF) method [44]. When the location of the free surface is unknown, this is regarded as the preferred course of action [33,39,[55][56][57]. In urban sewer systems, the majority of manholes are two-way constructions with straight or angled flow [48].…”

“…First, the CFD model is generally cost-effective and efficient and does not need to be concerned with scale effects. Evaluating the accuracy of the used CFD programs and modeling methods is the primary focus of many studies [26,[30][31][32][33][34][35]. A proven CFD model can be used as a design tool to optimize the design of sewer connections [36,37].…”