Design Optimizing and CFD Analysis for Radial Vortex Flow Controls Device (VFC)

Client: SuDS Enviro Ltd | Project: Leeds, UK

Project Overview

SuDS Enviro Ltd engaged us to design and simulate a set of Radial Vortex Flow Control (VFC) devices that control stormwater flows using a purely hydraulic mechanism—without moving parts, power, or complex control systems. These devices needed to manage both low and high flow conditions, enabling unrestricted flow at low volumes and inducing vortex-driven throttling during peak flows.

The objective was twofold:

Develop three optimized VFC units with different outlet diameters (Ø50mm, Ø75mm, Ø100mm, and extended to Ø125mm & Ø150mm).
Build a simulation-backed predictive tool capable of generating head–discharge data, orifice sizes, and manufacturing dimensions based on user input of design flow and head.

We approached this project in two phases—first focusing on establishing a validated baseline design, and then scaling that design into a full product range with predictive capability for future customizations.

The Challenge

Stormwater management devices like VFCs must perform under a wide range of conditions. The client's expectations were particularly demanding:

Zero power and no moving parts, yet reliably respond to both low and high flows.
A design that maximizes flushing without increasing blockage risks.
Self-cleaning characteristics, especially during high-flow vortex conditions.
Capability to throttle flow precisely to target discharge rates at specific head heights.
Seamless integration with SuDS infrastructure with minimal post-installation modification.

In addition, the client emphasized:

A cross-sectional area 3–6 times greater than traditional orifice plates.
A design with large internal openings to reduce the chance of clogging.
A need to simulate and visualize flow behavior, especially for kickback and flush thresholds.
A deliverable in the form of a locked Excel-based calculator, generating both numeric outputs and graphical performance curves for each unit size.

Our Solution

Geometric and Performance Modeling

We started with an existing 350mm cowl geometry and focused first on the 100mm outlet version (Unit 3). From there, other units were scaled proportionally, and geometric dependencies were established among the variables:

Outlet opening diameter
Swirl chamber width
Inlet height
Overall swirl diameter

CFD simulations were carried out in ANSYS to replicate real flow behavior. We monitored the formation of vortex patterns, pressure differentials, and flow regimes under various head conditions (0.1m to 2.5m).

The resulting data allowed us to:

Optimize the kickback point, ensuring the flow throttles only at the precise design head.
Adjust "Area A" to maintain a vertical flow increase profile and avoid premature bypassing.
Establish a buoyancy-driven emergency flushing mechanism that triggers when blockage threatens the main discharge, redirecting flow through a secondary path and clearing debris autonomously.

Simulation Setup and Parameters

The radial vortex unit was tested across various head values (from 0 to 2.5m) with fine mesh refinement and transient simulation. Key parameters:

Design Head: 0.77m
Design Flow: 235 L/s
Flushing Flow Requirement: 180 L/s

The simulations showed rapid vortex formation with well-developed air cores and high central backpressure. Flow visualization confirmed rotational symmetry, effective swirl generation, and minimal dead zones.

Development of Predictive Tool

In parallel, we developed an Excel-based simulation model using empirical correlations derived from CFD results. Users can input any design head and desired flow, and the tool automatically returns:

Required inlet size
Internal orifice diameter
Manufacturing specifications
A head–discharge curve (both graph and table)
Minimum sump depth, pipe diameter, and clearance dimensions

This tool ensures that future VFC designs can be generated and quoted quickly with simulation-backed accuracy.

Results & Benefits

The simulations for the 114mm LR3 unit revealed impressive performance:

Head (m)	Flow (L/s)
0.1	35.374
0.5	178.576
1.0	295.748
1.5	363.732
2.5	504.908

Key outcomes:

Flow control exceeded expectations, with a flushing flow 2–4× greater than minimum required, enabling rapid clearance of debris.
The emergency door system worked reliably, driven by buoyancy—not mechanical force—allowing for effective system reset and maintenance-free operation.
Flow curves were smooth, consistent, and scalable across all five unit sizes.
Blockage risk was minimized through:

Larger openings vs traditional orifices
Vortex-powered self-flushing
Emergency bypass with re-circulating vortex creation

Installation and maintenance considerations were also integrated:

Custom-fit unit housings
No need for moving components
Easy access via standard rodding points
316L stainless steel for durability against chemical and abrasion wear

Conclusion

This project with SuDS Enviro Ltd demonstrates how computational fluid dynamics and parametric modeling can transform product development in stormwater engineering. The LR3 series of Radial Vortex Flow Controls are now equipped with:

A validated and optimized geometric design
Reliable throttling across a wide head range
Self-maintaining flow characteristics
A user-friendly Excel tool for design and quoting

We've not only delivered a high-performing device family but also empowered the client with a repeatable design and quoting system for future applications.

The system is now ready for production and has been successfully validated against both performance benchmarks and practical deployment constraints. Next steps include physical prototyping, field testing, and scaling for additional head/flow combinations.

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Founder & Co-Founder of Airvitalize

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Managing Member at Megachip Solutions LLC

Solvo Engineers did an excellent job on our CFD project for airflow optimization in a dust catcher device. They carefully analyzed the design, improved efficiency by addressing critical flow issues, and clearly explained every step of their process. Their expertise and responsiveness made collaboration very smooth and effective.