🌡️ Condensation UDF

This UDF simulates vapor → liquid transformation when the local temperature is below saturation. It handles mass transfer and energy release due to condensation in multiphase cells.

  • 💧 Phase Transition: Vapor → Liquid
  • 🧊 Condition: Triggers when T < Tsat
  • ⚡ Energy Logic: Releases latent heat into the system
  • 📐 Interface Detection: Based on volume fraction of each phase
  • 🔁 Reset: Clears memory at end of timestep
Condensation UDF

🔥 Evaporation UDF

This UDF models liquid → vapor transition when temperatures rise above saturation. It simulates energy absorption and mass loss due to boiling or heating.

  • 🔥 Phase Transition: Liquid → Vapor
  • 🌡️ Condition: Triggers when T > Tsat
  • ❄️ Energy Logic: Absorbs latent heat from fluid
  • 🧠 Interface Check: Targets multiphase interface cells
  • 🧹 Cleanup: Resets UDMs at each timestep
Evaporation UDF

♻️ Combined Phase Change UDF

A single UDF that handles both condensation and evaporation based on whether T is above or below Tsat.

  • ♻️ Phase Transition: Vapor ⇄ Liquid
  • 🔀 Condition: Dynamically switches logic based on temp
  • 📊 Detection: Checks cell VOF + local temperature
  • 📘 Use Case: Transient thermal simulations
  • ✅ Bonus: Fully annotated and documented
Combined UDF

🧪 Comparing UDF Types for Phase Change

Technical breakdown of each UDF and how they behave under various thermal conditions:

💧 Condensation

Simulates vapor → liquid when T < Tsat.

  • ✔ Applies latent heat release
  • ✔ Simple and lightweight
  • ✘ No evaporation logic

🔥 Evaporation

Models liquid → vapor when T > Tsat.

  • ✔ Absorbs latent heat
  • ✔ Focused on boiling/thermal rise
  • ✘ No condensation behavior

♻️ Combined

Switches between both modes depending on temperature.

  • ✔ Fully dynamic (bi-directional)
  • ✔ Ideal for full heat cycles
  • 🧠 Slightly more complex logic