CFD TOPIC HUB · INTERNAL FLOW & PRESSURE DROP
Internal-flow CFD: connect pressure loss to the complete flow system.
Use this hub for ducts, pipes, manifolds and flow networks where pressure loss, flow split, turbulence, wall friction, local losses and boundary placement determine the engineering result.
Start from the decision the CFD model has to support.
A pressure-drop comparison is only meaningful when the pressure definition, stations, flow rate, characteristic length, roughness and local-loss scope are consistent between CFD and the reference calculation or experiment.
Use these checks before adding model complexity.
- Define pressure stations and total/static pressure consistently before comparing results.
- Use Reynolds number and hydraulic diameter consistently across friction and turbulence estimates.
- Check conservation and boundary sensitivity before attributing a mismatch to turbulence modelling.
Already have a CFD model that behaves incorrectly?
Start from the symptom and follow the Technical Case diagnostic sequence before tuning unrelated solver controls.
Browse Technical Cases →Build the modelling decision from the underlying physics.
Use the guides for definitions, assumptions, workflow design and evidence requirements.
Reynolds Number in CFD
Choose characteristic scales and interpret flow regime
Open resource →ENGINEERING GUIDECFD Verification vs Validation
Build evidence around the pressure-loss result
Open resource →ENGINEERING GUIDEReport CFD Boundary Conditions & Properties
Make the flow setup reproducible
Open resource →Diagnose the failure mode when the solved model disagrees.
Technical Cases are organized around symptoms, likely causes, diagnostic order and controlled fixes.
CFD Pressure Drop Does Not Match
Align stations, friction, roughness and local losses
Open resource →TECHNICAL CASEOutlet Boundary Too Close
Test domain-length sensitivity
Open resource →TECHNICAL CASEReverse Flow at a Pressure Outlet
Diagnose backflow and outlet placement
Open resource →TECHNICAL CASEInlet Turbulence Conditions Look Wrong
Connect intensity and length scale to RANS inputs
Open resource →TECHNICAL CASEMass Imbalance in CFD
Verify the complete control-volume balance
Open resource →Challenge the CFD with transparent engineering checks.
Independent calculations help reveal whether the problem is in the physics, inputs, numerical resolution or interpretation.
Reynolds Number Calculator
Check flow regime and similarity
Open resource →ENGINEERING TOOLHydraulic Diameter Calculator
Define the characteristic length consistently
Open resource →ENGINEERING TOOLPressure Drop Calculator
Build an analytical pressure-loss baseline
Open resource →ENGINEERING TOOLInternal Flow Workflow
Connect geometry, regime, loss and validation checks
Open resource →Continue with the same engineering context.
Move into structured training when you need the complete methodology, or engineering support when the answer depends on the actual project.
Connect adjacent modelling decisions.
Complex CFD problems often cross more than one topic cluster. Continue into the governing issue rather than searching by software menu alone.
Go deeper on a question engineers search when the model becomes uncertain.
These focused resources extend this topic cluster with one decision guide and one symptom-led Technical Case.
CFD Pressure Boundary Conditions
Choose pressure and flow boundaries from the physical system, with consistent static/total pressure definitions and enough freedom for the solver to determine the response.
Read guide →TECHNICAL CASEFlow Rate Is Wrong with Pressure Boundaries
Trace unexpected mass flow to pressure definitions, reference pressure, system resistance, properties, boundaries or conservation errors.
Open diagnostic case →