What each method answers
Finite element analysis (FEA) predicts how a solid part or structure responds to loads, temperature and vibration. It answers questions such as: will this bracket yield, how much will this plate deflect, where is the stress highest and how long will it last under repeated load.
Computational fluid dynamics (CFD) predicts how a liquid or gas moves and exchanges heat. It answers questions such as: how much pressure drop does this duct cause, is air reaching every part of this enclosure, where does a hot spot form and how evenly does a mixer blend.
Start from the decision, not the method
Before choosing, write down the decision the result will support: release a design, choose between two concepts, find the cause of a failure or size a component. The decision tells you how accurate the answer must be and which method can provide it.
If the question is about a solid part carrying load, FEA is the natural choice. If it is about what a fluid does, CFD is. Many real products need both, or a coupled study, for example a heat exchanger whose walls must also survive pressure and thermal expansion.
Typical use for each
Structural analysis: Brackets, frames, housings, shafts, weldments, pressure parts and fixtures. Static strength, stiffness, buckling, fatigue and vibration are common targets.
Thermal analysis: Heat conduction through solids and the stresses it causes. It is often used for housings, electronics enclosures and equipment that sees temperature cycling.
Flow analysis: Ducts, valves, pumps, fans, mixers, heat exchangers, cooling of enclosures and ventilation of rooms or plants. Pressure drop, flow distribution and temperature fields are common outputs.
What the simulation needs from you
Whatever the method, the quality of the answer depends on the quality of the inputs. Prepare the geometry in a state the analyst can use, and list the materials, the loads or flow conditions and the constraints or boundary conditions.
State the operating cases that matter, including the worst case. State what you will treat as acceptable: a stress limit, a deflection limit, a maximum temperature or a pressure drop. Without a pass mark, a result is only a picture.
Assumptions and validation
Every simulation simplifies reality. A good analysis report states the simplifications: which features were removed, how contacts and joints were treated and what the boundary conditions represent. Ask for them in writing.
Where you have test data from a similar design, share it. Matching a known result is the best way to build trust in a method before relying on it for a new design.
Briefing a simulation study
Send the model, a short description of how the product is used, the cases to run and the acceptance criteria. Agree what the report contains, for example the load cases, plots, a summary table and recommended changes.
Start with a defined, small study. It confirms that the analyst understands your intent and shows how the results will be presented. See our guide to writing an engineering brief, and our FEA and CFD analysis service.