03.monitor.md

Monitor

This document describes how to set up and use monitors in Flow360 simulations. Monitors allow you to track flow field variables at specific locations during the simulation, providing real-time feedback on how your solution is developing.

Available Options

Option	Description
Total Forces	Integrated forces and moments over all surfaces
Forces by surface	Force and moment distribution over individual surfaces
Heat transfer by surface	Heat transfer distribution over surfaces
BET Forces and Moments	Blade Element Theory forces and moments for rotors
BET Sectional Loading	Blade Element Theory radial distribution of forces and moments for rotors
Force distribution (Y)	Force distribution along the y-axis
Force distribution (X)	Force distribution along the x-axis
Actuator Disk	Forces and moments for actuator disk models

Detailed Descriptions

Total Forces

Total Forces monitor calculates the integrated forces and moments over all surfaces in the computational domain.

Axis settings:

Axis	Available Values
X-axis	pseudo step (for steady state simulation) physical step (for unsteady simulation)
Y-axis	CL CD CFx CFy CFz CMx CMy CMz CLPressure CDPressure CFxPressure CFyPressure CFzPressure CMxPressure CMyPressure CMzPressure CLSkinFriction CDSkinFriction CFxSkinFriction CFySkinFriction CFzSkinFriction CMxSkinFriction CMySkinFriction CMzSkinFriction

Notes:

• Provides overall aerodynamic performance metrics
• Calculates lift, drag, and moment coefficients
• Available for both steady and unsteady simulations

Forces by surface

Forces by Surface monitor provides detailed force and moment distribution over individual surfaces.

Axis settings:

Axis	Available Values
X-axis	pseudo step (for steady state simulation) physical step (for unsteady simulation)
Y-axis	CL CD CFx CFy CFz CMx CMy CMz CLPressure CDPressure CFxPressure CFyPressure CFzPressure CMxPressure CMyPressure CMzPressure CLSkinFriction CDSkinFriction CFxSkinFriction CFySkinFriction CFzSkinFriction CMxSkinFriction CMySkinFriction CMzSkinFriction
Series	Available wall-type surfaces

Notes:

• Useful for analyzing contribution of different components
• Provides local force and moment coefficients
• Supports both steady and unsteady simulations

Heat transfer by surface

Heat Transfer by Surface monitor calculates heat transfer distribution over surfaces.

Axis settings:

Axis	Available Values
X-axis	pseudo step (for steady state simulation) physical step (for unsteady simulation)
Y-axis	HeatTransferRate
Series	Available wall-type surfaces

Notes:

• Provides local heat flux and heat transfer coefficients
• Useful for thermal analysis
• Available for both steady and unsteady simulations

BET (Blade Element Theory) Analysis

BET analysis provides two types of monitors for rotor analysis:

• Forces and Moments

  • Calculates forces and moments for each blade element
  • Provides detailed rotor performance metrics
  • Available for both steady and unsteady simulations

  Axis settings:

  Axis	Available Values
  Disk	Available BET disks
  X-axis	pseudo step (for steady state simulation) physical step (for unsteady simulation)
  Y-axis	Force_x Force_y Force_z Moment_x Moment_y Moment_z

• Sectional Loading

  • Shows radial distribution of forces and moments
  • Useful for analyzing blade loading
  • Provides insight into rotor performance across the span

  Axis settings:

  Axis	Available Values
  Disk	Available BET Disks
  X-axis	radius
  Y-axis	ThrustCoeff TorqueCoeff
  Series	Blades available for selected Disk

Force distribution

Force distribution monitors provide spanwise and chordwise force distributions:

• Y-Direction distribution

  • Shows force distribution along the y-axis
  • Useful for analyzing spanwise loading
  • Provides sectional force coefficients

  Axis settings:

  Axis	Available Values
  X-axis	Y
  Y-axis	CMy_per_span CFx_per_span CFz_per_span
  Series	Available wall-type surfaces

• X-Direction distribution

  • Shows force distribution along the x-axis
  • Useful for analyzing chordwise loading
  • Provides sectional force coefficients

  Axis settings:

  Axis	Available Values
  X-axis	X
  Y-axis	CD_per_length Cumulative_CD_Curve
  Series	Available wall-type surfaces

Actuator Disk

Actuator Disk monitor calculates forces and moments for actuator disk models.

Axis settings:

Axis	Available Values
X-axis	pseudo step (for steady state simulation) physical step (for unsteady simulation)
Y-axis	Power Force Moment
Series	Available actuator disks

Notes:

• Provides integrated forces and moments
• Useful for simplified rotor modeling
• Available for both steady and unsteady simulations

Available Output Fields

The following table lists all available output fields that can be monitored in Flow360, along with their descriptions and units:

Output	Description
Force Monitors
CD	Drag coefficient (force parallel to freestream direction)
CL	Lift coefficient (force perpendicular to freestream direction)
CS	Side force coefficient (force perpendicular to lift and drag)
CMx	Rolling moment coefficient (moment about x-axis)
CMy	Pitching moment coefficient (moment about y-axis)
CMz	Yawing moment coefficient (moment about z-axis)
CFx	Force coefficient in x-direction (body-fixed coordinate system)
CFy	Force coefficient in y-direction (body-fixed coordinate system)
CFz	Force coefficient in z-direction (body-fixed coordinate system)
Heat Transfer Monitors
HeatTransferRate	Heat flux through surface
BET Analysis
ThrustCoeff	Thrust coefficient (normalized axial force on rotor)
TorqueCoeff	Torque coefficient (normalized moment about rotation axis)
Force Distribution
CMy_per_span	Sectional pitching moment coefficient per unit span
CFx_per_span	Sectional force coefficient in x-direction per unit span
CFz_per_span	Sectional force coefficient in z-direction per unit span
CD_per_length	Sectional drag coefficient per unit length
Cumulative_CD_Curve	Integrated drag coefficient from leading edge to current position
Actuator Disk
Power	Power generated/consumed by actuator disk
Force	Force vector generated by actuator disk
Moment	Moment vector generated by actuator disk

These outputs are dimensionless in the case of coefficients, while others use our own unit system. To learn more about non-dimensional outputs, refer to documentation.

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💡 Tips

• Use force monitors to track convergence of aerodynamic coefficients
• Monitor heat transfer for thermal analysis and cooling system design
• BET analysis provides detailed insight into rotor performance
• Force distribution monitors help identify critical loading regions
• Actuator disk monitors are useful for simplified rotor modeling

Best Practices for Force Analysis

• Monitor both total and component-specific forces
• Use force distribution monitors to identify critical regions
• Monitor forces at key operating conditions
• Compare results with experimental data when available

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❓ Frequently Asked Questions

• What is the difference between Total Forces and Forces by Surface?

  Total Forces provides overall aerodynamic performance metrics, while Forces by Surface gives detailed distribution over individual components.

• How do I interpret BET analysis results?

  BET analysis provides both integrated forces/moments and sectional loading, helping understand rotor performance at both global and local scales.

• What monitors should I use for thermal analysis?

  Use Heat Transfer by Surface monitor to track heat flux and heat transfer coefficients over surfaces.

• How do I analyze force distributions?

  Use X and Y direction force distribution monitors to understand spanwise and chordwise loading patterns.

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🐍 Python Example Usage

Below is a Python code example showing how to access force monitors:

import flow360 as fl

case = fl.Case(id="case-XXXXX") # provide a valid case id
case.wait() # wait for the case to finish running
results = case.results

# Force monitor
total_forces = results.total_forces
print(total_forces)

# Surface force monitor
surface_forces = results.surface_forces
print(surface_forces)

# BET monitor
bet_forces = results.bet_forces
print(bet_forces)