Simcenter STAR-CCM+ In-cylinder Solution

Simcenter STAR-CCM+ In-cylinder Solution provides a simplified approach within Simcenter STAR-CCM+ to perform transient moving-mesh simulations of internal combustion engines (ICE).

Simcenter STAR-CCM+ In-cylinder accesses a subset of Simcenter STAR-CCM+ features that are relevant to motored-test, charge-motion, and combustion simulations. A key feature of Simcenter STAR-CCM+ In-cylinder is the provision of Engine Parts. Engine Parts allow you to define the geometry, physics, and motion of your engine components in an efficient and compact way. Engine Parts are available for cylinders, cylinder sectors, valves, injectors, ignitors, and plenums. Plenums allow you to model additional engine components that are static and attached to the engine, such as gas admission valves for the injection of gaseous fuels or pre-chambers for jet ignition.

The motion of the mesh is modeled using a morph-map approach. This approach redistributes the mesh vertices in response to the movement of the piston and the valves. Based on specific mesh quality criteria, Simcenter STAR-CCM+ In-cylinder automatically re-meshes the engine geometry and maps the solution onto the new mesh. The interpolation method conserves mass, momentum, and total energy over the engine volume.

The Simcenter STAR-CCM+ In-cylinder user interface contains several ordered nodes that you work through sequentially. In the background, Simcenter STAR-CCM+ In-cylinder defines the models and parameters that are required for the analysis in the Simcenter STAR-CCM+ simulation tree.

You do not require a detailed knowledge of CFD or Simcenter STAR-CCM+ in order to use the tool. However, you still have access to the full functionality of Simcenter STAR-CCM+ at any stage if you want to modify your model or account for more complex scenarios.

Simcenter STAR-CCM+ In-cylinder is part of the Simcenter STAR-CCM+ installation. However, you require specific licensing to launch Simcenter STAR-CCM+ In-cylinder.

For Simcenter STAR-CCM+ In-cylinder simulations, you require a double-precision version of Simcenter STAR-CCM+.
For practical examples of ICE simulations using Simcenter STAR-CCM+ In-cylinder, refer to the following tutorials:

Inside Simcenter STAR-CCM+ In-cylinder

The main features of Simcenter STAR-CCM+ In-cylinder are:

Geometry

  • Import of CAD data
  • Import of 2D sector spline for cylinder sector model

Physics

  • Time: transient calculations
  • Time-step: constant, stepped table, or automatic
  • Solution domain: single-domain
  • Air material: single-component or multi-component gas
  • Equation of state: ideal gas or real gas (Redlich-Kwong)
  • Heat transfer modes: conduction and convection (forced and buoyancy driven)
  • Flow regime: turbulent (RANS or LES)
  • Gravity effects: optional
  • Conjugate heat transfer (CHT): File-based coupling of in-cylinder simulation with solid thermal analysis in Simcenter STAR-CCM+ or a third-party tool

Conditions

  • Geometry: full, half-engine (with symmetry), or cylinder sector (with periodicity)
  • Cycle length: 360 deg or 720 deg
  • Initialization: import tabular pressure and temperature data
  • Flow boundaries: pressure outlets using tabular pressure and temperature data
  • Wall boundaries: thermal and wall surface specification

Motion

  • Cylinder motion: calculates piston position from engine geometry and operating conditions
  • Valves motion: import valve lift curves

Fuel Injection

  • Spray modeling: Lagrangian multiphase
  • Injector types: hollow/solid cone injector or nozzle injector with one or multiple nozzles
  • Injection strategy: single-pulse or multi-pulse injection
  • Fuel mass flow rate: constant mass flow rate with start and end of fuel injection or import of tabular data
  • Initial fuel temperature: constant or import tabular data
  • Initial droplet diameter: constant, import tabular data (CDF or PDF), or Rosin-Rammler distribution function
  • Droplet shape: spherical
  • Fuel material: single-component or multi-component liquid
  • Equation of state for fuel droplets: constant density
  • Phase change: vapor diffusion limited evaporation without condensation
  • Droplet-gas interaction: two-way coupling
  • Droplet forces: drag, pressure gradient, virtual mass, and turbulent dispersion
  • Wall impingement mode: Bai-Gosman with formation of liquid film on walls (optional)
  • Primary atomization: Huh (optional)
  • Secondary breakup: KHRT or Reitz-Diwakar (optional)

Combustion

  • Combustion of liquid or gaseous fuels
  • Combustion models: Extended Coherent Flame Model Three Zone (ECFM-3Z), Extended Coherent Flame Model with Combustion Limited by Equilibrium Enthalpy (ECFM-CLEH), Specified Burn Rate, or Complex Chemistry
  • Pollutant emission: CO, NOx, and soot
  • Ignition: periodic spark ignition (FI Spark Ignition or ISSIM Spark Ignition) with optional knock or auto ignition
  • Gas composition initialization: manual or automatic as a function of the equivalence ratio and the exhaust gas recirculation (EGR) percentage

Mesh

  • Volume mesh: trimmed cell mesher (predominantly hexahedral cells)
  • Prism layers: prismatic cells on walls for boundary flow accuracy
  • Cell size: based on best practices
  • Mesh refinement zones for valves, cylinder chamfer, and piston crevice
  • Mesh extrusion at flow boundaries (optional)
  • Mesh reuse for multi-cycle simulations

Solve

  • Segregated solver for flow and energy
  • Algorithm for pressure-velocity coupling: SIMPLE or PISO
  • Solver under-relaxation
  • Live monitoring of solution data

Results

  • Visualization of geometry, mesh, and solution data
  • Access to solution data through plane sections that are positioned and oriented based on the engine geometry
  • Plots for characteristics of the in-cylinder flow, such as swirl, x-tumble, and y-tumble
  • Reports for summaries of the simulation and its runtime, such as start of fuel injection (SOI) and elapsed time of the analysis.