THRUST: Mobile CFD

THRUST is a two-dimensional computational fluid dynamics (CFD) solver with conjugate heat transfer that runs live on your iPad. Draw a domain, place solid bodies and heat sources, set the boundaries and press Run: flow and temperature develop on screen while you move blocks, change materials or switch the field you are looking at. SOLVER • Lattice Boltzmann method (D2Q9, two-relaxation-time) for incompressible flow, with an optional Smagorinsky subgrid model for laminar runs. • Conjugate heat transfer: one enthalpy-based lattice spans fluid and solids, so temperature and heat flux are continuous across every interface. • Buoyancy, and temperature- and pressure-dependent properties. • Optional turbulence models: mixing length, standard k-ε or SST k-ω, with wall functions for velocity and heat, wall roughness and optional buoyancy production of turbulence, and SST k-ω with laminar–turbulent transition. • Boiling and condensation (optional, for pure fluids such as water): boiling at heated walls, condensation in colder liquid, film boiling and rewetting, with vapor carried and drifting in the liquid. • Grid refinement: finer cells, up to three levels, around chosen walls and blocks. • Runs on the iPad's GPU through Metal, about 130–180 million lattice updates per second on an iPad mini (A17 Pro). SET-UP • Boundaries: inlets with uniform, parabolic or turbulent profiles, outlets, no-slip and free-slip walls that can be heated or held at a temperature, open boundaries to still surroundings, and periodic sides. • Solid blocks (rectangles with optional rounded corners, circles, ellipses, triangles, elbows and polygons) that conduct heat, generate heat or are held at a fixed temperature; fluid blocks that heat or cool the fluid inside them. • Pumps: a fluid block can drive the flow with four-quadrant characteristic curves (head and torque, edited in the app or imported from CSV), at a set speed, coasting down after a trip, or following its own inertia. • Flow resistances: a loss coefficient on a fluid block stands in for a blockage, a screen or a valve. • Time tables: heat sources, temperatures, loss coefficients, inlet flows and wall heat can follow a table over time, for transients such as a power ramp or a closing valve. • Fluids: air and water tables built in, plus 127 fluids from the CoolProp library. • Materials: 37 metals, alloys, ceramics, glasses and plastics from published tables, an insulator, or your own. RESULTS • Fields: temperature, speed, gauge, static, dynamic and stagnation pressure, total head, vorticity, the turbulence model's k and ε or ω, wall y⁺, the vapor void fraction, and velocity vectors and streamlines. • Probes with time histories, snapshots and statistics, including wall heat flux, wall shear stress, y⁺ and void fraction. • An exact energy balance: heat in through each edge, heat generated, heat stored and heat taken up by boiling. • Export images, field data (CSV, VTK for ParaView), and probe and energy histories (CSV). • Save a run with its results and continue it later, or on another device. VALIDATED The solver is checked against analytic solutions and published benchmarks, for example natural convection in a heated cavity (de Vahl Davis) within 0.5 % and the vortex-shedding Strouhal number behind a cylinder at Re ≈ 100 (0.168 against 0.164). With boiling, the void along a heated channel follows published measurements at seven pressures without a mean bias. The user guide explains the methods and their limits; its Validation page lists every case. Twenty-two ready-made scenarios: cooled electronics, a heated cavity, cooling fins, a cylinder wake, a backward-facing step, an impinging jet, a ventilated room, a pump loop whose flow reverses, fully developed periodic cells (a heated channel, a ribbed channel, a tube bank, offset strip fins, a heated slot) and four boiling cases. No account, no network connection and no data collection: everything runs and stays on your iPad.