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Solver Configuration

Configure your OpenFOAM simulation parameters using the Navier AI Platform’s guided interface. The platform organizes solver settings into logical groups accessible through the simulation tree or search commands.

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Configuration Overview

The solver configuration is organized into these main areas:
  1. Solver Settings: Core simulation parameters and computational settings
  2. Fluid Domain: Flow field properties and boundary conditions
  3. Turbulence: Turbulence model selection and parameters
  4. Thermophysical Properties: Compressible flow thermodynamics (when applicable)
  5. Boundary Conditions: Surface boundary condition assignments
Access any configuration popup via:
  • Search Box: Ctrl+K → type the setting name
  • Simulation Tree: Click items under “Simulation” section
  • Toolbar: Direct access to common settings

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Solver Settings

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Access

  • Search: Ctrl+K → “Solver Settings”
  • Tree: Simulation → Solver
  • Popup: Core simulation parameters

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Available Parameters

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Simulation Category

Options:
- Flow: Standard fluid dynamics simulation
- Particles: Lagrangian particle tracking (specialized applications)

Default: Flow

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Compressibility

Options:
- Incompressible: Constant density flow (most applications)
- Compressible: Variable density with thermodynamics

Selection Criteria:
- Incompressible: Mach < 0.3, minimal heating
- Compressible: Mach > 0.3, significant temperature effects

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Simulation Mode

Options:
- Steady State: Time-independent solution
- Transient: Time-accurate simulation

Note: Transient mode has additional timestep controls

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Time Controls

Start Time
  • Default: 0 seconds
  • Usually left at zero for steady-state simulations
End Time
  • Steady State: Represents iteration count (e.g., 1000 = 1000 iterations)
  • Transient: Physical simulation time in seconds
  • Typical Range: 100-3000 for steady state
Timestep (Δt)
  • Steady State: Pseudo-timestep for stability (usually 1.0)
  • Transient: Physical timestep in seconds
  • Auto-calculated based on mesh and flow conditions
Write Interval
  • Steady State: Save solution every N iterations (e.g., 50-100)
  • Transient: Save interval in seconds
  • Balance storage needs vs. monitoring frequency

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Computational Settings

Number of Cores
  • Range: 2-64 cores
  • Default: 3 cores
  • Guidelines:
    • 2-4 cores: < 5M cells
    • 4-8 cores: 5-15M cells
    • 8+ cores: > 15M cells
Initialize with PotentialFoam
  • Toggle: Enabled/Disabled
  • Default: Enabled (recommended)
  • Benefits: Faster convergence, better initial conditions
  • Use: Highly recommended for external aerodynamics
Adjust Timestep (Transient Only)
  • Automatic timestep adjustment for stability
  • Based on Courant number limits
Max Courant Number (Transient Only)
  • Controls timestep adaptation
  • Typical: 0.5-2.0 for stability

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Fluid Domain Properties

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Access

  • Search: Ctrl+K → “Fluid Domain”
  • Tree: Simulation → Fluid Domain
  • Popup: Flow field properties and conditions

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Core Parameters

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Velocity (U)

Vector Field: [Ux, Uy, Uz] in m/s
- Ux: X-direction velocity (typically forward flight)
- Uy: Y-direction velocity (crosswind/sideslip)  
- Uz: Z-direction velocity (vertical component)

Typical Values:
- Automotive: [20-50, 0, 0] m/s
- Drone flight: [10-30, 0, 0] m/s
- Building wind: [5-20, 0, 0] m/s

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Pressure

The pressure field type depends on compressibility: Incompressible Flow
  • Kinematic Pressure (p): Units of m²/s²
  • Represents pressure divided by density
  • Default: 0 (gauge pressure)
Compressible Flow
  • Static Pressure (p): Units of Pa
  • Absolute pressure value
  • Default: 101,325 Pa (atmospheric)

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Temperature (Compressible Only)

Temperature (T): Kelvin
- Default: 293.15 K (20°C)
- Range: Depends on application
- Required for compressible flow thermodynamics

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Viscosity

The viscosity field depends on compressibility: Incompressible Flow
  • Kinematic Viscosity (ν): m²/s
  • Default: 1.5e-5 m²/s (air at 20°C)
Compressible Flow
  • Dynamic Viscosity (μ): Pa·s
  • Default: 1.846e-5 Pa·s (air at 20°C)

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Additional Compressible Properties

When compressible flow is selected:
  • Molecular Weight (M): g/mol (default: 28.97 for air)
  • Specific Heat (Cp): J/(kg·K) (default: 1005 for air)
  • Enthalpy of Formation (Hf): J/kg (default: 0)
  • Prandtl Number (Pr): dimensionless (default: 0.71)

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Turbulence Configuration

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Access

  • Search: Ctrl+K → “Turbulence”
  • Tree: Simulation → Turbulence
  • Popup: Turbulence model and parameters

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Available Turbulence Models

Description: Shear Stress Transport model
Best for: External aerodynamics, separated flows
Parameters:
- k: Turbulent Kinetic Energy (m²/s²)
- ω: Specific Dissipation Rate (1/s)  
- νt: Turbulent Kinematic Viscosity (m²/s)

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Spalart-Allmaras

Description: One-equation model
Best for: Airfoil flows, aerospace applications
Parameters:
- ν̃: Modified turbulent viscosity (m²/s)
- νt: Turbulent Kinematic Viscosity (m²/s)

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Turbulence Parameter Guidelines

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For k-ω SST Model

Typical Values for External Flows:
- k: 0.1-1.0 m²/s² (3-5% of mean kinetic energy)
- ω: 1-10 1/s (based on length scale and k)
- νt: 1-100 (turbulent/laminar viscosity ratio)

Calculation Helpers:
- k ≈ 1.5 × (U × I)² where I = turbulence intensity
- ω ≈ k^0.5 / L where L = turbulence length scale

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Turbulence Intensity Guidelines

Flow Environment:
- Wind tunnel: 0.1-0.5%
- Free stream: 1-5%  
- Urban environment: 10-20%
- Internal flows: 5-15%

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Thermophysical Properties (Compressible Only)

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Access

  • Search: Ctrl+K → “Thermophysical Properties”
  • Tree: Simulation → Thermophysical (when compressible selected)
  • Popup: Thermodynamic model settings
This popup is only available when “Compressible” is selected in Solver Settings.

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Available Models

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Thermophysical Model Type

Options:
- hePsiThermo: Enthalpy-based, pressure-density relation
- heRhoThermo: Enthalpy-based, direct density
- Mixture variants: For multi-component flows

Default: hePsiThermo (recommended for most applications)

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Transport Properties

Options:
- const: Constant transport properties
- sutherland: Temperature-dependent (gases)
- polynomial: Polynomial temperature dependence

Default: const (simplest, often adequate)

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Equation of State

Options:
- perfectGas: Ideal gas law (most common)
- icoPolynomial: Incompressible polynomial

Default: perfectGas

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Boundary Conditions

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Access

  • Search: Ctrl+K → “Boundary Conditions”
  • Tree: Simulation → Boundary Conditions (when available)
  • Popup: Surface boundary condition assignment

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Domain Boundaries (Automatic)

The platform automatically assigns appropriate boundary conditions to domain faces: 
External Flow Configuration:
- Inlet (X-min): Velocity inlet with specified flow conditions
- Outlet (X-max): Pressure outlet (zero gauge pressure)
- Sides (Y±, Z±): Slip walls or symmetry conditions

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Geometry Surface Conditions

Automatic Assignments:
- Solid surfaces: No-slip wall conditions
- Turbulence: Appropriate wall functions applied
- Heat transfer: Adiabatic walls (no heat flux)

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Advanced Boundary Settings

Available boundary condition types:
  • Fixed Value: Specified constant value
  • Zero Gradient: No normal gradient
  • Inlet/Outlet: Prevents backflow
  • Wall Functions: Automatic turbulence treatment
  • Symmetry: Mirror boundary

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Application-Specific Recommendations

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External Aerodynamics (Drones, Vehicles)

Recommended Settings:
- Simulation Category: Flow
- Compressibility: Incompressible
- Simulation Mode: Steady State
- End Time: 1000-2000 iterations
- Turbulence Model: k-ω SST
- Initialize with PotentialFoam: Enabled

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Compressible Flow (High-Speed)

Recommended Settings:  
- Simulation Category: Flow
- Compressibility: Compressible
- Simulation Mode: Steady State
- End Time: 2000-3000 iterations
- Turbulence Model: k-ω SST
- Thermophysical: hePsiThermo + perfectGas

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Internal Flows

Recommended Settings:
- Simulation Category: Flow  
- Compressibility: Incompressible
- Simulation Mode: Steady State
- End Time: 1500-2500 iterations
- Turbulence Model: k-ω SST
- Higher turbulence levels: 5-15%

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Convergence and Monitoring

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Automatic Monitoring

The platform provides real-time convergence tracking:
  • Residual plots: All equation residuals
  • Force coefficients: Drag, lift, moment evolution
  • Mass conservation: Inlet/outlet flow balance
  • Iteration progress: Completion percentage

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Convergence Criteria

Target Residuals:
- Momentum: < 1e-4
- Pressure: < 1e-4  
- Turbulence: < 1e-5
- Energy: < 1e-6 (compressible)

Force Stability:
- < 0.1% variation over 100 iterations

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Best Practices

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Setup Strategy

  1. Start Simple: Begin with default settings for your application type
  2. Validate Configuration: Check parameter values against physical expectations
  3. Monitor Convergence: Watch residuals and forces during simulation
  4. Iterate Settings: Adjust based on convergence behavior

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Common Settings by Application

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Drone Aerodynamics

  • Incompressible flow, k-ω SST turbulence
  • Velocity: 10-30 m/s, low turbulence intensity
  • Potential flow initialization recommended

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Automotive

  • Incompressible flow, k-ω SST turbulence
  • Velocity: 20-50 m/s, moderate turbulence
  • Steady state with ~2000 iterations

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High-Speed Aircraft

  • Compressible flow, thermophysical properties
  • Static pressure and temperature specified
  • Higher iteration counts (3000+)
Next Steps: With solver configuration complete, proceed to run your simulation and monitor convergence through the platform’s real-time diagnostics.