Computational fluid dynamics study of flow depth in an open Venturi channel for Newtonian fluid

Abstract

Open Venturi channel flow measurement could be a cheap method to be used in drill bit pressure control. The main objective of this study is to identify the factors related with the flow depth in an open Venturi channel. A commercial computational fluid dynamics tool was used for the simulations. The simulation results were validated with the previous related experimental results. The agreement between simulation and experimental data was satisfactory. The open Venturi channel at a horizontal angle gave a higher flow depth before the contraction region compared to its negative angles (downward). When the channel inclination angle was reduced, flow velocity increased and flow depth reduced. Likewise, flow became supercritical and created a hydraulic jump. The wall roughness played a significant role with the starting position of the hydraulic jump. This was due to the energy loss between wall and fluid. There is an energy loss in a hydraulic jump, when the supercritical flow transition into the subcritical flow. Large eddies were generated in a hydraulic jump. Flow depths difference between supercritical and subcritical is a factor to generate the large eddies. Fine meshes gave sharp interfaces, which was similar to what is seen in reality. The difference turbulence models: standard k-ε model, k-ω model, k-ε RNG model and k-ε realizable model gave almost the same flow depths.

A solution method for one-dimensional shallow water equations using flux limiter centered scheme for open Venturi channels

“…The wall-reflection pressureforce causes the flow regime to change from supercritical flow to subcritical flow in the hydraulic jump. 16 The wall-reflection pressure-force coming from the contraction walls reduces the speed of the upstream flow, which causes the change in the flow regime. Figure 6 shows the quasi-steady state results, following Figure 5.…”

“…Further, the result of the modified SWE result was compared to a CFD result. 16 interface. [17][18][19] Time discretization is based on the implicit Euler method for a transient calculation.…”

“…A comparison with 3D CFD result with the modified and the conventional shallow water results, quasi-steady state, the flow rate at 100 kg/min. The CFD result is from Welahettige et al 16 CFD: computational fluid dynamics.…”

“…With the channel at the horizontal plane, this hydraulic jump propagation was caused only by the wall-reflection pressure–force and friction–force effects. 10,16 According to the critical depth calculation in Welahettige et al., 10 the average critical flow depth before the contraction region is 48.4 mm. Figure 5 shows a dynamic situation of the flow profile.…”

One-dimensional model of turbulent flow of non-Newtonian drilling mud in non-prismatic channels

“…Supercritical and subcritical flow regimes can, where the channel is horizontal, be observed occurring simultaneously before and after the Venturi region (Welahettige et al 2017a, b). Higher-order Godunov-type numerical schemes are recommended for solving the open-channel conservation equations due to the following issues: unsteady hydraulic jump propagation, to avoid negative flow depth (reduce numerical viscosity) and maintain stability at dry or near-dry conditions (Sanders and Iahr 2001;Kurganov and Petrova 2007).…”