Achieve more reliable CFD simulations with Meancalc
Running high-fidelity CFD simulations can be time consuming and computationally intensive. Whether you’re simulating external aerodynamics for a motorsport vehicle or automotive car, truck, bike or boat, you’ve likely encountered the same fundamental question:
How long should the simulation run?
If the simulation runs too short, the results can be unreliable. If it runs too long, you waste valuable core hours with little to no additional benefit. That’s where Meancalc, a smart run-time control tool from Upstream CFD, comes in. Now fully integrated into bramble, Meancalc helps engineers achieve reliable CFD simulations by default, automatically and efficiently.
Who’s behind Meancalc?
Upstream CFD is a team of engineers focused on making simulation smarter, not just faster. Their work has already been key to projects like the DrivAerML dataset, where hundreds of high-fidelity vehicle simulations were run with consistent statistical accuracy and without wasting compute.
Their mission is clear: streamline and strengthen CFD workflows through intelligent automation. Meancalc is a major step toward that goal, built to help engineers produce reliable results at lower cost.
What is Meancalc?
Meancalc is an intelligent run-time control tool for CFD simulations. It does two critical things:
- Automatically detects when the initial transient has passed
(so your time-averaged results aren’t biased) - Continuously checks for statistical convergence
(and stops the simulation as soon as your target accuracy is reached)
In other words, Meancalc eliminates the guesswork. You no longer have to manually determine when to start or stop averaging. It does the job for you, dynamically, during the run, delivering more accurate and reliable CFD simulations with no additional input.
Why should CFD engineers care?
Because your simulation time and budget aren’t unlimited. With Meancalc, you can:
- Improve accuracy: No more averaging over unsteady startup periods or stopping before convergence.
- Reduce cost: For the same statistical accuracy, Meancalc reduced compute cost by over 5× in the DrivAerML project.
- Save time: No need for post-run convergence checks or re-runs due to under-sampling.
- Run leaner: Only use as many time steps as are truly needed, case-by-case.
In bramble, where many users are running large-scale simulations (e.g., DES for external aerodynamics), Meancalc ensures every core hour contributes meaningfully to final results, boosting both efficiency and reliability.
How do I use it?
It’s easy.
When setting up your simulation workflow in bramble, just select the Meancalc methodology from the dropdown menu.
That’s it, no scripting, no tuning. It integrates seamlessly with your run and handles the logic in the background.
How much does it cost?
The integration adds a minimal cost of just £0.003 per core-hour, bringing the total to £0.065 per core-hour when using standard public cloud, slightly above the base bramble rate of £0.062 per core-hour. For most users, the savings from shorter, more accurate simulations far outweigh this small extra cost, while helping you achieve reliable CFD simulations every time.
Ready, steady, go
If you’re ready to give it a go, just start a new run in bramble and select Meancalc from the workflow dropdown.
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