neqsim-fem-coupling

name	neqsim-fem-coupling
calculation_basis	screening
version	0.2.0
description	Link a NeqSim process simulation and engineering documents to a finite-element model of the solid: heat conduction through a layered wall, transient cooldown, species diffusion in porous rock, and the thermal and pressure stress that follow. Merges P&ID, STID, datasheet, insulation-specification and inspection inputs into a traceable design basis, converts a flashed NeqSim fluid into a film coefficient, a Biot and Fourier number and a mesh and time-step target, solves the layered one-dimensional problem with a dependency-free finite-element solver verified against the closed-form resistance, generates a structured Gmsh mesh in two dimensions or swept into three (revolved pipe or vessel wall, extruded plate or block) and a runnable scikit-fem or FEniCSx case, screens which backend is defensible (scikit-fem, FEniCSx, SfePy, MFEM, OpenSeesPy, PyNite), renders the mesh and the solved field off-screen with PyVista including surface, cut-plane and clipped three-dimensional views, gates the study on discretisation, mesh independence, energy balance and boundary placement, and reduces the field to the U-value, U-multiplier, hot-spot factor and no-touch time a one-dimensional NeqSim model consumes. USE WHEN: a task needs a temperature or stress field inside a solid that a one-dimensional heat-transfer coefficient cannot produce - a local insulation defect, a support or clamp short-circuit, a buried or non-radial soil path, a nozzle or wall discontinuity, a cooldown or thermal-shock transient, diffusion through a porous medium - when a three-dimensional geometry or a rendered field is needed, or when an existing thermal or stress finite-element report must be qualified before its numbers are trusted.
last_verified	2026-08-08
requires	{"python_packages":[],"java_packages":[],"env":[],"network":[]}

FEM Coupling

NeqSim solves the fluid. It reports a bulk temperature, a pressure and a set of transport properties, and a one-dimensional model turns those into a single U-value per pipe section. That works until the geometry stops being one-dimensional: a section of insulation floods, a clamp bridges the coating, a line is buried under a sloping seabed, a nozzle interrupts a shell. The heat then spreads in a direction the one-dimensional model does not have, and the U-value it was given is wrong by an amount nobody can estimate by hand.

This skill closes that gap. It takes whatever is known about the component (P&ID, STID tag register, datasheets, insulation specification, inspection report), takes the fluid side from a NeqSim flash, builds and solves the finite-element model of the solid, and converts the field back into the number the one-dimensional model needed - an effective U-value, a multiplier on it, a hot-spot factor, a no-touch time, a wall stress. When a thermal or stress finite-element study already exists, it qualifies that study instead of running a new one.

It is the solid-side companion to neqsim-cfd-coupling: same design-basis discipline, same quality gate before any number is quoted, same handoff back into a one-dimensional model. CFD resolves the fluid; FEM resolves the solid.

Every layer works on its own. NeqSim, Gmsh, scikit-fem and FEniCSx are all optional: without NeqSim the fluid state is stated directly, and without a mesher or a solver the geometry and the case are still written, with the commands needed to run them elsewhere.

When to Use

• A one-dimensional U-value is being assumed where the geometry is not one-dimensional: a local insulation defect or flooded section, a support or clamp, a buried line, a valve or flange with no insulation.
• A cooldown or no-touch time is needed and the wall's thermal inertia matters, not just the fluid's.
• A metal temperature is needed for a thermal-stress, MDMT or material-selection question, and the process-to-ambient difference is not the metal gradient.
• Species diffusion through a porous medium is being modelled and the molecular diffusivity has to come from the actual mixture.
• A thermal or thermo-mechanical finite-element report is attached to an equipment tag and its numbers are about to be used.
• A new finite-element run is being specified and needs film coefficients, a penetration depth, an element size and a time step.

When Not to Use

• As a substitute for a qualified stress or thermal analyst on a design decision. This is a screening and coupling toolkit, not a code-compliance calculation.
• For fatigue life, fracture mechanics, creep, plasticity, buckling or contact. The stress layer produces elastic thermal and pressure stresses with a category attached; it does not perform a code assessment.