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Computational Fluid Dynamics

Advanced CFD simulation services to optimise your water treatment processes, improve equipment design, and solve complex fluid flow challenges.

Scientific Modelling & Simulation

Behind the design sits a full modelling toolkit — CFD, process simulation, biokinetic (ASM/ADM), reaction-kinetics, hydraulic, limnological and data-driven digital-twin modelling. We pick, or combine, the disciplines that answer your question and validate them against real data.

Explore Scientific Modelling

The Power of Computational Fluid Dynamics

Computational Fluid Dynamics (CFD) is a powerful engineering tool that uses numerical methods to simulate and analyse fluid flow, heat transfer, and related phenomena. In water treatment, CFD enables us to visualise and optimise processes that are difficult or impossible to observe directly — resolving velocity, pressure, turbulence, particle paths and temperature at millions of points inside the equipment before a single component is fabricated.

10M+Mesh cells in a typical production study
<10%Validation error vs. pilot & field data
30–60%Chemical & energy savings unlocked
3–5×Faster design iteration than physical prototyping

Anatomy of a CFD Study

Every project moves through the same disciplined pipeline — from raw geometry to a validated, decision-ready result.

1. Scope

Define the question, targets, and the physics that matter.

2. Geometry

Build or clean the 3D fluid domain from CAD or scans.

3. Mesh

Discretise into millions of cells; refine boundary layers.

4. Solve

Set physics, boundary conditions, and converge the solver.

5. Validate

Check mesh independence, balances, and field data.

6. Optimise

Translate the flow field into design actions.

Comprehensive Simulation Solutions

From initial concept to optimisation, Reynolds & Bauhm provides end-to-end CFD services tailored to your water treatment challenges.

Flow Simulation & Analysis

Comprehensive computational fluid dynamics simulations to analyse flow patterns, velocity distributions, and pressure drops in water treatment systems and process equipment.

  • Steady-state and transient analysis
  • Multi-phase flow modelling
  • Turbulence modelling (RANS, LES, DNS)
  • Velocity and pressure field mapping

Mixing & Mass Transfer Optimisation

CFD-based optimisation of mixing efficiency, chemical dosing distribution, and mass transfer processes in reactors, tanks, and treatment vessels.

  • Mixing time analysis
  • Chemical distribution studies
  • Residence time distribution
  • Mass transfer coefficient evaluation

Particle & Sedimentation Analysis

Discrete phase modelling to track particle behaviour, settling patterns, and separation efficiency in clarifiers, thickeners, and filtration systems.

  • Particle trajectory tracking
  • Settling velocity analysis
  • Separation efficiency prediction
  • Sludge accumulation modelling

Equipment Design Validation

Virtual prototyping and performance validation of custom equipment designs before fabrication, reducing development requirements and time-to-market.

  • Design optimisation studies
  • Performance benchmarking
  • Scale-up validation
  • What-if scenario analysis

Aeration & Gas Transfer Modelling

Multiphase gas–liquid CFD of bubble plumes, oxygen transfer, and gas dispersion in aeration basins, DAF units, and gas-mixed reactors to maximise transfer efficiency and minimise blower energy.

  • Bubble dynamics & plume modelling
  • Oxygen transfer (kLa) prediction
  • Gas hold-up & dispersion studies
  • DAF micro-bubble performance

Thermal & Energy Analysis

Conjugate heat-transfer and energy CFD to map temperature fields, evaluate heating and cooling duty, and reduce energy demand in digesters, thermal hydrolysis, and process tanks.

  • Conjugate heat-transfer modelling
  • Temperature distribution mapping
  • Heating & cooling duty evaluation
  • Energy efficiency optimisation

CFD in Water Treatment Equipment

Our CFD expertise spans the full range of water treatment processes and equipment.

Clarifiers & Settling Tanks

Optimise flow distribution, prevent short-circuiting, and maximise settling efficiency.

  • Reduce hydraulic loading issues
  • Improve solids removal
  • Optimise weir design

DAF Systems

Analyse bubble distribution, contact zone efficiency, and separation performance in DAF units and DAF with lamella packs.

  • Optimise bubble size distribution
  • Improve contact efficiency
  • Reduce energy consumption

Mixing Tanks & Reactors

Ensure uniform mixing, optimise impeller design, and minimise dead zones.

  • Reduce mixing time
  • Optimise power input
  • Improve chemical distribution

Sedimentation Basins

Model sludge blanket behaviour and optimise sludge removal systems.

  • Prevent sludge washout
  • Optimise collection mechanism
  • Improve effluent quality

Screening Equipment

Analyse flow patterns and optimise screen design for maximum efficiency.

  • Reduce head loss
  • Optimise slot configuration
  • Improve debris capture

Piping & Distribution Systems

Minimise pressure drops and ensure uniform flow distribution.

  • Reduce pumping costs
  • Prevent flow maldistribution
  • Optimise pipe sizing

What CFD Reveals That You Can't See

Inside an opaque steel tank, the difference between 78% and 94% removal is a flow pattern no probe can map. CFD makes it visible — and fixable.

Short-Circuiting

A fast jet races from inlet to outlet, bypassing the treatment zone.

CFD maps the dead zones and the jet, so a redesigned inlet baffle restores plug-flow and recovers retention time.

Uneven Mixing

Stagnant pockets leave chemical undispersed and reactions incomplete.

Impeller and dosing-point studies cut mixing time and dead volume, so every drop of reagent works.

Particle Carry-Over

Solids escape the settling zone and breach the effluent weir.

Discrete-phase tracking predicts settling paths, so geometry tweaks raise capture efficiency without a bigger tank.

Choosing the Right Turbulence Model

Model choice is driven by the flow physics, not convenience. Picking wrong is the most common cause of confidently-wrong CFD — here is how we match the model to the problem.

k-ω SSTWorkhorse

Blends near-wall accuracy with free-stream stability. Our default for adverse pressure gradients, separation, and confined jets.

DAF contact zonesImpeller flowsNozzles & diffusers

Realizable k-εRobust

Efficient and stable for fully-developed, high-Reynolds flows where wall detail is less critical.

Pipe networksDistribution headersLarge basins

LES / SASTransient

Resolves large turbulent eddies in time for genuinely unsteady physics — at higher computational cost.

Vortex sheddingUnsteady separationAcoustic sources

Reynolds Stress (RSM)Anisotropic

Solves each turbulent stress component for flows with strong streamline curvature and swirl.

Cyclonic separatorsStrong swirlSecondary flows

Physics & Solver Capability

A full multiphysics toolkit, applied to the water, wastewater, and thermal problems that matter.

Multiphase Flow

  • Volume of Fluid (VOF) free surfaces
  • Euler-Euler bubble columns
  • Discrete Phase / DPM particle tracking
  • Cavitation & gas hold-up

Heat & Mass Transfer

  • Conjugate heat transfer (CHT)
  • Species transport & reactions
  • Evaporation, condensation, drying
  • Buoyancy & natural convection

Moving & Reacting

  • MRF & sliding-mesh rotation
  • Overset / dynamic meshing
  • Biokinetic coupling (ASM/ADM)
  • Population balance (bubble/floc size)

Methods & Compute

  • RANS, URANS, LES, hybrid
  • High-performance cluster solving
  • Design-of-Experiments & optimisation
  • Digital-twin & reduced-order models

How We Work

Our systematic approach ensures accurate simulations and actionable results.

01

Problem Definition

Understand objectives, constraints, and define simulation scope.

02

Geometry & Mesh

Create 3D geometry and generate high-quality computational mesh.

03

Simulation Setup

Define boundary conditions, turbulence models, and solver settings.

04

Analysis & Validation

Run simulations, analyse results, and validate against data.

05

Reporting & Optimisation

Deliver comprehensive reports with optimisation recommendations.

CFD Validation Protocol

Every simulation we deliver follows a rigorous, documented validation protocol to ensure predictions are trustworthy, reproducible, and legally defensible.

Our validation framework aligns with AIAA G-077-1998, ASME V&V 20, and ISO/IEC 17025 principles. Each project milestone is gated by quantified acceptance criteria before proceeding to the next phase.

Validation StageAcceptance CriterionMetric / ThresholdMethod
Geometry VerificationCAD-to-mesh deviation< 0.1% volume differenceBoolean comparison, STL tolerance check
Mesh IndependenceGrid Convergence Index (GCI)GCI < 5% on key outputRichardson extrapolation, 3 mesh levels
Time Step IndependenceTemporal convergence< 2% change on halving ΔtDual-timestep comparison
Turbulence Model Selectiony+ complianceWall y+ = 1 – 5 (resolved) or 30 – 300 (wall function)Wall-adjacent cell inspection
Mass BalanceGlobal continuity< 0.01% imbalanceFlux reporting, inlet vs outlet
Momentum BalanceForce convergence< 0.5% residual oscillationDrag/lift monitor stability over 500 iterations
Experimental CorrelationValidation error|E| < 10% vs. experimental dataPoint probe, traverse line, or full-field PIV
Uncertainty QuantificationInput parameter sensitivitySobol index > 0.1 flaggedDesign of Experiments (DoE), 50+ runs

Mesh Independence Study

We solve on three systematically refined meshes — coarse, medium, and fine — typically at 1.4× cell count ratio. Richardson extrapolation estimates the zero-grid solution. Only results with GCI < 5% on critical outputs (pressure drop, separation efficiency, mixing time) are accepted.

GCI = Fs |ε| / (rp − 1)

Fs = 1.25 (safety factor), r = 1.4 (refinement ratio), p = 2 (observed order)

Turbulence Model Selection

Model choice is driven by flow physics, not convenience. k-ω SST for adverse pressure gradients and separation; Realizable k-ε for free shear flows; LES for transient vortex shedding; RSM for strong swirl. Wall treatment verified via y+ mapping.

  • k-ω SST — DAF contact zones, impeller flows
  • Realizable k-ε — Pipe networks, distribution headers
  • LES / SAS — Unsteady separation, vortex shedding
  • RSM — Cyclonic separators, strong swirl

Experimental Validation

Where physical data exists, we correlate against pilot test results, manufacturer performance curves, or published benchmark studies. Validation error is reported as:

E = (CFD − Exp) / Exp × 100%

Target: |E| < 10% on velocity, pressure, and concentration fields

Uncertainty Quantification

Input parameters (flow rate, temperature, particle size distribution, chemical dosing) carry manufacturing and operational tolerances. We run sensitivity matrices to quantify output uncertainty and identify which inputs drive performance variance.

  • Monte Carlo sampling: 1,000+ realisations
  • Sobol sensitivity indices for ranking
  • 95% confidence intervals on predictions
  • Tornado charts for executive reporting

Example: DAF Unit Validation Gate

A 50 m³/hr DAF unit simulated for a poultry processing client:

Mesh GCI

3.2% on rise velocity

Mass Balance

0.003% imbalance

y+ Compliance

98.4% cells in 1–5 range

Validation Error

6.8% vs. pilot TSS removal

Result: All gates passed. Design approved for fabrication with 95% confidence interval on hydraulic loading: 42–58 m³/hr.

Brewery DAF CFD Optimisation

How CFD-guided design modifications achieved 94% TSS removal and 62% chemical reduction

ClientUK Regional Craft BreweryApplicationDAF — Brewery Wastewater Pretreatment
ResultTSS Removal 78% → 94%chemical reduction62% ferric chloride reduction
Read Full Case StudyAll Case Studies

Related Services

Combine CFD analysis with our other engineering services for comprehensive project delivery.

Equipment Optimised with CFD

Engineered for Performance

DAF Systems

CFD-optimised flow distribution for maximum efficiency.

Explore Physico-Chemical

LAMELLA Separator

Optimised plate spacing and flow patterns.

View Lamella Separator

Desalination Systems

CFD analysis for RO pre-treatment optimisation.

Desalination Plant Solutions

Water Aeration

Optimised aerator design for maximum oxygen transfer.

Water Aeration

CFD Across Our Equipment Range

Almost every unit we build hides a flow, mixing, or thermal problem that CFD can resolve. Here is where it adds the most value across our catalogue — each unit links to its equipment page.

Separation & Clarification

Flow distribution, rise/settling velocity, and short-circuiting control set the separation efficiency of every clarifier and flotation unit.

Mixing, Dosing & Coagulation

Impeller and injection-point CFD eliminates dead zones and shear, so reagent disperses fast and floc grows without breaking.

Biological Reactors & Aeration

Multiphase CFD predicts gas hold-up, oxygen transfer (SOTE), and mixing in aerated and anaerobic reactors — the heart of biological treatment.

Membranes & Advanced Polishing

CFD maps feed-channel velocity, concentration polarisation, and UV/ozone contactor hydraulics to lift flux and dose efficiency.

Screening & Pumping

Head-loss, approach-velocity, and NPSH studies keep screens free-flowing and pumps clear of cavitation.

Thermal & Mass-Transfer Units

Conjugate heat transfer and phase-change CFD optimise temperature uniformity, fouling, and stripping efficiency.

CFD Engineering Resources

Deep-dive engineering guides for specific equipment and processes

DAF CFD Optimisation

Complete CFD-driven design guide for Dissolved Air Flotation systems. Covers bubble size distribution modelling, contact zone hydraulics, white-water nozzle optimisation, surface loading validation, and energy minimisation through hydraulic profiling.

  • Bubble-particle contact efficiency modelling
  • Nozzle velocity profiling & maldistribution correction
  • Surface loading rate vs. rise velocity correlation
  • Validated case studies: food, poultry, oil & gas
View Guide

Lamella Separator CFD

Plate settler hydraulic optimisation using CFD. Inlet duct design to prevent jetting, sludge hopper circulation analysis, and effluent weir uniformity targets. Includes Reynolds-number-dependent plate spacing recommendations.

  • Inlet energy dissipation & flow distribution
  • Plate angle & spacing sensitivity study
  • Sludge removal cycle optimisation
  • Design calculation spreadsheets
View Guide

Aeration System CFD

Oxygen transfer efficiency prediction through multiphase CFD. Bubble size distribution, gas hold-up profiles, and SOTE (Standard Oxygen Transfer Efficiency) correlation for fine-bubble diffusers, surface aerators, and jet aeration.

  • Multiphase Euler-Euler bubble modelling
  • Gas hold-up & bubble residence time
  • SOTE correlation vs. ASCE standard
  • Energy consumption per kg O2 transferred
View Guide
Browse All Engineering Resources

CFD Thermal Simulation Services

Conjugate heat transfer modelling for equipment and processes where temperature control is critical to performance, efficiency, and safety.

Heat Exchanger Optimisation

Plate, shell-and-tube, and spiral heat exchanger thermal performance with fouling prediction and energy efficiency analysis.

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Cooling Tower Performance

Evaporative cooling simulation with spray droplet tracking, fill pack optimisation, and fan power reduction.

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Thermal Mixing Analysis

Transient temperature uniformity in tanks, reactors, and vessels. Eliminate stratification and hot spots.

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Evaporation & Drying

Phase-change thermal modelling for evaporators, crystallisers, and sludge dryers with energy optimisation.

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Bioreactor Temperature

Heat generation and removal in biological reactors. Maintain optimal mesophilic conditions for maximum COD removal.

Learn More

Power Plant Cooling

Condenser, cooling tower, and heat recovery steam generator thermal analysis for maximum cycle efficiency.

Learn More

Ready to optimise your process with CFD?

Contact Our Engineers of CFD experts to discuss your simulation requirements.

Industries We Serve

Our expertise spans multiple industries with sector-specific water treatment solutions.