Simulation configuration¶

Bramble describes a simulation with three reusable pieces of configuration:

• Template Cases define how to simulate: the CFD recipe.
• Maps define which conditions to simulate: the list of Attitudes.
• Kinematic Setups define how the model moves between those conditions.

Keeping them separate means you can run the same model over many conditions, or the same conditions over many models, without rebuilding anything.

Template Cases¶

A Template Case is a recipe that makes setting up correct CFD simulations quick and repeatable.

Building a CFD model from the ground up is complicated, repetitive and time-consuming. It is also prone to human error that may not show up until after a simulation (or several) has finished, if at all.

A Template Case avoids this. It is a predefined recipe that Bramble uses to create each simulation with the right settings automatically.

Created by experts. A Template Case is usually written by an experienced CFD engineer and shared across the Account.

Encapsulates best practice. Once written, a Template Case captures best practice, so both CFD specialists and less experienced users produce results that can be trusted.

A Template Case configures things such as:

• solver type and solution stages (for example potential → RANS, or RANS → DES), with duration
• the mesh recipe and refinement
• domain size
• boundary conditions, applied to zones
• force and flow measurements
• radiators and porous media
• exports

Template Cases are uploaded as Python (.py) files and can be edited in Bramble's Template Case editor. Each belongs to a Methodology Group, such as OpenFOAM. The group decides which features the editor offers. When you configure an Attitude you choose a methodology (the solver and version) and a workflow (the solve type, such as RANS or DES). The Template Case must suit both.

Maps¶

A Map lists sets of parameters, such as velocity or yaw. Each set becomes an Attitude when the Map is used in a Run.

A Map can hold one Attitude or many, each with its own parameter values. Every Attitude produces its own forces and flow visualisations. By default the parameters are front and rear ride height, velocity, yaw, roll and steer. Your Account may have a different set.

Optional for a single condition. A Run doesn't need a Map. Without one, the Run gets a single Attitude named after the Run, and its velocity comes from the Template Case. A Kinematic Setup is optional too.

Easily create sweeps. Bramble can generate sweeps of Attitudes across parameter ranges automatically.

Advanced features. Maps also let you configure following vehicles, extra parameters such as cornering radius, and swapping Parts per Attitude with Attitude Specific Geometry.

Kinematic Setups¶

Kinematics means motion. A Kinematic Setup defines how the parts of a model move and how the model sits relative to the flow.

Default parameters. A Kinematic Setup sets default values for core parameters such as velocity, yaw, and front and rear ride height. A Map overrides these for each Attitude.

Coordinate systems. A Kinematic Setup defines the coordinate systems that drive movement in the model. Examples are the rotation axis of a wheel, or the ground plane for an external aerodynamics simulation.

Moving Parts. Bramble can translate and rotate Parts for each Attitude. That lets it steer wheels or move a car's suspension without you creating new CAD.