Dashboard

Dashboard#

The Flow360 dashboard provides real-time monitoring capabilities for CFD simulations, offering visualization of convergence metrics and aerodynamic coefficients. This document describes the key features and interpretation of the dashboard components.

Nonlinear Residuals Monitor#

The nonlinear residuals monitor displays the convergence history of the simulation, presenting both absolute and relative residuals for key flow variables:

  • cont: Continuity equation residual

  • momx: X-momentum equation residual

  • momy: Y-momentum equation residual

  • momz: Z-momentum equation residual

  • ener: Energy equation residual

  • nuHat: Turbulence model - modified viscosity residual (SA exclusive)

  • k: Turbulence model - turbulence kinetic energy residual (SST exclusive)

  • omega: Turbulence model - specific dissipation rate residual (SST exclusive)

The residuals are plotted on a logarithmic scale against physical time steps, allowing users to:

  • Monitor convergence behavior

  • Assess solution stability

  • Determine when steady-state has been achieved

Interpretation Guide#

  • Decreasing residuals indicate proper convergence

  • Oscillatory behavior may suggest physical unsteadiness or numerical issues

  • Plateauing residuals might indicate reaching machine precision or solution stagnation

Interactive Features#

  • Toggle between absolute and relative non-linear residual views

  • Select and deselect individual residuals

  • Choose a time range on the bottom bar of the residuals plot

  • Save residuals data as an image

Forces and Moments#

Lift and Drag Coefficients#

  • CL: Lift coefficient

  • CD: Drag coefficient

Force Coefficients in Component Directions#

  • CFx: X-direction force coefficient

  • CFy: Y-direction force coefficient

  • CFz: Z-direction force coefficient

Moment Coefficients#

  • CMx: Rolling moment coefficient

  • CMy: Pitching moment coefficient

  • CMz: Yawing moment coefficient

Statistics#

The dashboard provides statistical data for force coefficients, averaged over the last 10% of steps. This feature helps in:

  • Determining final converged values

  • Assessing solution stability

  • Quantifying solution uncertainty

  • Making informed decisions about simulation completion

Time history#

Each coefficient is plotted against physical time steps, enabling:

  • Real-time monitoring of aerodynamic performance

  • Assessment of force and moment convergence

  • Identification of periodic behaviors or instabilities

  • Verification of expected aerodynamic characteristics

Interactive Features#

  • Click on a plot to enlarge it

💡 Tips

  1. Convergence Assessment

    • Monitor both residuals and force coefficients

    • Look for at least 3-4 orders of magnitude drop in residuals

    • Verify force coefficient stability

  2. Solution Validation

    • Compare force coefficients with expected ranges

    • Check for physical consistency in moment coefficients

    • Verify symmetry properties where applicable

  3. Troubleshooting

    • Use residual behavior to identify numerical issues

    • Monitor force oscillations for physical unsteadiness

    • Cross-reference with mesh quality metrics when necessary

❓ Frequently Asked Questions

  • Why are my residuals not decreasing?

    This could be due to several factors, examples include:

    • Insufficient mesh quality in critical regions

    • Inappropriate CFL number settings

    • Physical instabilities in the flow

    • Incorrect boundary conditions

  • What is considered a “converged” solution?

    A solution is typically considered converged when:

    • Residuals have dropped by 3-4 orders of magnitude

    • Force coefficients have stabilized (variations < 0.1%)

    • The solution behavior matches expected physical trends

  • How do I interpret oscillating force coefficients?

    Oscillating force coefficients may indicate:

    • Natural flow unsteadiness (e.g., vortex shedding)

    • Need for time-accurate simulation

    • Numerical instabilities

    Check if the frequency of oscillations matches expected physical phenomena.

  • Can I export the dashboard data?

    Yes, you can:

    • Save residuals plot as image using the download button

    • Export numerical data in CSV format using the assets window

    • Use Python API to download simulation results

  • Why do some residuals plateau while others continue decreasing?

    This is common and can occur due to:

    • Machine precision limitations

    • Local flow features affecting specific equations

    As long as force coefficients are stable, this usually isn’t concerning.

  • How do I zoom in on a specific time range?

    Use the bottom bar of the residuals plot to:

    • Click and drag to select a time range

    • Use the handles to adjust the range

    • Click to change your range’s position

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