Computational fluid dynamics for chemical injection, rapid mixing and dosing dynamics — we simulate where the reagent goes, how fast it disperses, and whether it actually reaches every part of the flow before it reacts. From coagulant injection quills and static mixers to pulsation from diaphragm metering pumps and antiscalant dosing into high-salinity seawater, CFD turns dosing from a rule-of-thumb into a verified design.
Most dosing failures are mixing failures. A perfectly-calculated dose is useless if the reagent streaks down one side of the pipe, short-circuits past the reaction zone, or hits a dead pocket where it over-concentrates and scales. The window for coagulant charge-neutralisation is well under a second; pH and disinfectant reactions need uniform contact within a defined residence time. CFD resolves the injection plume, the turbulent dispersion, the velocity gradient (G) and the residence-time distribution so the injection point, quill geometry, static-mixer selection and run-length are sized to deliver complete, uniform dosing — not assumed to.
Plume trajectory, jet penetration and back-mixing from injection quills and diffusers — so the reagent reaches the pipe centre, not just the wall.
Velocity-gradient (G) and mixing-energy mapping for in-line static mixers and mechanical flash mixers, with pressure-drop trade-off.
RTD and dead-zone detection in flocculation tanks and contact chambers — finding short-circuiting that wastes reagent and breaches contact time.
Transient CFD of the pulsing flow from diaphragm/metering pumps — how stroke frequency and pulsation dampening affect instantaneous concentration.
Species transport coupled to mixing so the model shows where charge neutralisation, pH shift or disinfectant CT is actually achieved.
Coagulant-then-polymer or acid-then-caustic injection spacing, confirming each reagent disperses before the next is added.
Diaphragm metering pumps don’t dose a smooth stream — they pulse
A diaphragm or solenoid metering pump delivers reagent as a series of discrete pulses, not a continuous flow. Between strokes the instantaneous dose drops to zero; at the stroke it spikes. Into a fast-moving main this can mean alternating slugs of over- and under-dosed water unless the pulse is damped and mixed. Transient CFD shows the real instantaneous concentration field, letting us size the pulsation damper, set the stroke frequency for the duty, and place the injection where turbulent dispersion smooths the pulses before the analyser or reaction zone.
| Pulse-dosing variable | What the CFD shows | Design outcome |
|---|---|---|
| Stroke frequency | Slug spacing & concentration ripple | Higher frequency / smaller stroke for smoother dosing |
| Pulsation damper | Residual ripple after damping | Damper sizing to hit a concentration tolerance |
| Injection point & turbulence | How fast pulses blend into the main | Run-length / mixer to flatten the pulse |
| Analyser placement | Where concentration is representative | Probe position for stable closed-loop control |
Mixing & injection design · Dosing control strategy · Dosing pump selection
Antiscalant, coagulant and acid injection on the desalination intake
Dosing into a seawater intake adds physics that fresh-water dosing doesn’t have. The high density and salinity of seawater changes how a lighter reagent plume rises and disperses; large intake pipe diameters make centre-line penetration hard; and the chemicals — antiscalant, ferric coagulant, acid — must be uniform before they reach the UF/RO membranes or they fail to protect them. CFD models the buoyant plume, the cross-sectional uniformity at the mixer outlet, and the injection-to-membrane blending so the dose actually does its job. It pairs directly with our DAF pre-treatment and seawater DAF pilot work.
Confirms even antiscalant concentration across the full pipe section before the membranes — no streak that leaves part of the flow unprotected.
Models how the reagent plume behaves in dense saline water, including buoyant rise and stratification in large intake mains.
Ferric/PACl injection ahead of DAF or media filtration, sized for charge neutralisation in the available run-length.
Desalination intake dosing · Intake systems · Antiscalant dosing
Contour plots of reagent concentration through the mixing zone and across the pipe section.
Coefficient-of-variation at the mixer outlet against the target (typically CoV < 0.05).
Quill design, injection point and the straight run / mixer needed to hit uniformity.
Mixer pressure loss so the dosing pump and hydraulics are sized correctly.
Send us the line size, flow, reagent and duty — we will model the injection and mixing, and return the quill, mixer and run-length that deliver a uniform, effective dose.
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