5 Simple Projects to Build with EasyCFD_GComputational fluid dynamics (CFD) can feel intimidating at first: large meshes, long runtimes, and piles of numerical settings. EasyCFD_G is designed to lower that barrier — offering a streamlined interface, sensible defaults, and useful templates so you can focus on learning CFD concepts and building practical projects. Below are five approachable projects that will help you gain confidence with EasyCFD_G while teaching core CFD skills: geometry setup, meshing, boundary conditions, solution control, and post-processing. Each project includes objectives, step-by-step guidance, tips for accuracy, and suggestions for ways to extend the project as your skills grow.
Project 1 — Flow Around a Cylinder (2D)
Objectives
- Learn geometry creation and simple 2D meshing.
- Study boundary layers and vortex shedding (Kármán vortex street).
- Practice transient simulation and basic post-processing.
Step-by-step
- Create geometry: a rectangular channel with a circular cylinder centered vertically. Typical size: length = 10D, height = 4D, cylinder diameter = D.
- Define mesh: refine near the cylinder and wake region. Use boundary-layer prism layers if available. Aim for y+ < 1 near the cylinder if resolving the viscous sublayer; otherwise use wall functions and coarser mesh.
- Set physics: incompressible laminar or low-Re turbulent model depending on Reynolds number (Re = U∞ D / ν). For Re ≈ 100, laminar; for Re = 1000–10,000, select an appropriate turbulence model (k–ω SST is a good default).
- Boundary conditions: velocity inlet on the upstream face, pressure outlet downstream, no-slip on cylinder and walls, symmetry (or slip) on top/bottom if modeling an open channel.
- Solution control: for transient runs, choose a time step small enough to resolve vortex shedding (Δt ≲ 0.1*D/U∞). Run several shedding cycles.
- Post-processing: plot vorticity contours, lift/drag coefficients over time, and streamlines to visualize the wake.
Tips for accuracy
- Perform a mesh convergence study: run at least three mesh densities and compare mean drag coefficient.
- Monitor forces and residuals; ensure physical convergence before analyzing results.
Extensions
- Add rotation to the cylinder to examine the Magnus effect.
- Simulate heat transfer by enabling energy equation and setting different cylinder temperature.
Project 2 — Lid-Driven Cavity
Objectives
- Understand basic incompressible flow behavior and boundary layers in a simple geometry.
- Practice steady vs. transient solution strategies and verify against classic benchmark solutions.
Step-by-step
- Create a square cavity domain (1×1 non-dimensionalized).
- Mesh: structured quadrilateral mesh works well. Refine near the moving lid.
- Physics: incompressible Navier–Stokes. Choose laminar unless exploring higher Re.
- Boundary conditions: top lid moves with constant horizontal velocity (u=1), other walls are stationary no-slip.
- Solution: many classic results are steady for low Re; for higher Re you may see unsteady behavior. Use relaxation and under-relaxation for steady solvers; choose appropriate time step for transient.
- Post-processing: velocity profiles through centerlines, streamfunction contours, and comparison to benchmark data (e.g., Ghia et al.).
Tips for accuracy
- Use fine resolution near walls to capture boundary layers.
- Validate your centerline velocity profiles against published benchmarks.
Extensions
- Make the lid oscillatory to study driven unsteady flows.
- Introduce a heated lid and solve conjugate heat transfer.
Project 3 — Flow Through a Sudden Expansion (Pressure Loss & Recirculation)
Objectives
- Explore separation, recirculation zones, and pressure recovery.
- Practice applying pressure boundary conditions and measuring losses.
Step-by-step
- Geometry: straight channel that suddenly expands to a wider section (e.g., 1:2 area ratio).
- Mesh: refine in expansion region and walls where separation occurs.
- Physics: incompressible flow, laminar or turbulent based on Reynolds number.
- Boundary conditions: velocity inlet, pressure outlet, no-slip walls.
- Solution: converge steady-state solution if flow is steady; for higher Re, transient may be required.
- Post-processing: visualize recirculation zones with streamlines, plot pressure recovery along centerline, compute loss coefficient.
Tips for accuracy
- Use sufficiently long downstream domain so recirculation zones can develop and decay.
Extensions
- Add a curved expansion to see effects of geometry smoothing.
- Compare different turbulence models for predicting reattachment length.
Project 4 — Conjugate Heat Transfer in a Heated Pipe Section
Objectives
- Combine fluid flow and heat conduction in solids.
- Learn to set solid domains, thermal boundary conditions, and interpret temperature fields.
Step-by-step
- Geometry: a short pipe section with a solid wall thickness; can be 2D axisymmetric for simplicity.
- Mesh: ensure mesh compatibility or appropriate interface coupling between fluid and solid. Refine near wall.
- Physics: incompressible flow + energy equation in fluid; heat conduction in solid. Define properties (density, cp, k) for both domains.
- Boundary conditions: velocity inlet with specified temperature, heated outer wall (constant heat flux or temperature), pressure outlet.
- Solution: steady-state for constant inputs; transient if heating varies with time.
- Post-processing: surface temperature distribution, Nusselt number along the pipe, and heat flux vectors.
Tips for accuracy
- Use conjugate coupling with matched meshes or conservatively-interpolated interfaces.
Extensions
- Add internal fins to study enhanced heat transfer.
- Simulate turbulent flow and compare turbulent heat transfer correlations.
Project 5 — Mixing in a T-Junction
Objectives
- Study scalar transport (species or temperature), mixing efficiency, and interaction between inlet flows.
- Practice using tracer species, concentration boundary conditions, and mixing metrics.
Step-by-step
- Geometry: T-junction where two inlet channels meet and flow into a common outlet.
- Mesh: refine near junction and along mixing region; consider 3D for realistic mixing.
- Physics: incompressible flow with scalar transport (species concentration or temperature). Include diffusion.
- Boundary conditions: two inlets with different concentrations (e.g., 0 and 1), outlet pressure, no-slip walls.
- Solution: transient or steady depending on Peclet number; for high Peclet, transient/advection-dominated behavior requires stabilization schemes.
- Post-processing: concentration contours, calculate mixing index (e.g., coefficient of variation) along cross-sections downstream.
Tips for accuracy
- Ensure sufficient resolution to capture concentration gradients; consider higher-order advection schemes to reduce numerical diffusion.
Extensions
- Add pulsatile inlet flows to enhance mixing.
- Introduce reactive species with simple first-order reaction kinetics.
Choosing the Right Settings in EasyCFD_G
- For beginners, use the default k–ω SST turbulence model for external flows and the k–ε family for internal flows when speed is important.
- Start with coarser meshes to explore setup quickly, then refine selectively where gradients are large.
- Use built-in probes/monitors for forces, centerline velocities, and species concentrations to track convergence.
Workflow Tips
- Save templates of successful cases (geometry + boundary conditions) to reuse for new projects.
- Automate mesh refinement and parameter sweeps where possible to run convergence studies overnight.
- Keep notes of solver settings and mesh sizes — reproducibility matters more than raw performance.
Final thoughts
These five projects cover a broad set of CFD fundamentals while staying approachable. Start with the cylinder and cavity to get comfortable, then progress to conjugate heat transfer and mixing as you gain confidence. Each project offers clear extensions so you can grow your skills without getting overwhelmed.
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