CFD at RES

Alice Ely, 1st June 2017

Early days

Small to medium sites

Simple to moderately complex terrain

Temperate climates

Forestry

• Plenty of time for R&D and to analyse each individual site

• 2/3 CFD Analysts across RES’s regions

• Primarily for site conditions (turbulence, shear, inflow angles)

VENTOS® CFD software is developed by FEUP, University of

Porto under a joint venture with RES and Natural Power

Progress

Wind Flow - Automated internal

software developed 2013

• R&D project with validation carried out for

numerous sites

• Efficient system with short touch and flow

times per project

• Works well for the majority of sites

• Tier 2 support provided by CFD Specialists

when requiredBut at the same time…

Want CFD to be used for energy yield

prediction on every site

Need a system that everyone can use

to get results quickly!

• Atmospheric stability important

• Wider regional effects important

• More sites require Tier 2 support

Changing site conditions

Large sites

Extremely complex terrain

Varying climates – hot, cold, coastal

Forestry

Growing need for value focused R&D – no

budget for R&D without real world application

What are we doing

to improve quality

and performance?

Standard automated CFD setup is no longer

suitable for the majority of sites

Standard Model Improvements

• Developing a semi-automated Tier 2 support system

• Training analysts across RES’s regions to provide basic Tier 2 support

• Improving the current Tier 2 methodology to reduce non-convergence issues

• Introducing mixed stability CFD modelling in Wind Flow using VENTOS®’s

simple stratification model

But this is not the complete solution for large sites with challenging climates…

Ventos/M

• Currently impractical due to the high computational cost

• Routine calculations are still not feasible

• Provides coupling of WRF mesoscale simulations with VENTOS®

CFD software

• Have previously demonstrated benefits in various R&D projects

e.g. cold climate modelling in Sweden

• Automated tool developed for generating full virtual mast data

(RVM+)

• Model validation carried out (limited at present)`

Ideal solution – use VENTOS®/M

So what is stopping us using VENTOS®/M more frequently?

• Initially, establish as improvement to existing RVM+ virtual mast tool

• Potentially expand for other purposes e.g. wind maps, to support mesoscale map

validation in complex terrain

Implementing a statistical extension method

as a bridge until computational cost falls

Alternatives and Other CFD Tools

MPP 1

MPP 2

MPP 3

MPP 3a (alternative)

MPP 3b (alternative)

Combined Mesoscale Point Prediction

(MPP) and VENTOS® CFD extrapolation

• Make use of RES’s established WRF mapping

MPP tool

• Use on large sites with insufficient or no masts

to avoid extrapolating over large distances

with CFD alone

• Takes regional conditions and stability into

account via WRF model and complex terrain

via CFD

• Reduces computational time and chance of

CFD run failure on large sites

CFD Remote Sensing Correction

• Improve quality by allowing correction of remote sensing data in situations where the

flow is mildly complex

• Reduce waste by avoiding deploying remote sensing in extreme locations where it is

unlikely to work

• Important overall cost reduction

Any questions?

Alice Ely

Technical Analyst & CFD Specialist

Beaufort Court, Kings Langley

D +44 (0)1923 299318

alice.ely@res-group.com

Thank you.