12.5.1. CFX Plot Line Variables

While not all variable types are available at any given time, the following is a complete list of all variable types available for monitoring a CFX run. The specific plot line variables available for a given run are categorized by type.

For details on the output of the solver, see CFX-Solver Files.

Variable Name

Description

AERODYNAMIC DAMPING

Flutter calculations are important analysis tools in the design of modern turbines, compressors, and/or fan rotors. The aerodynamic damping factor is the most important result for these calculations. These results are later used to predict failures due to flutter, and to estimate component life cycles. Note that in order to monitor the aerodynamic damping, aerodynamic damping monitor objects must be created in CFX-Pre according to Setting up Monitors to Check Results in the CFX-Solver Modeling Guide. For further information, refer to sections Aerodynamic Damping in the CFX-Pre User's Guide through [Aerodynamic Damping Name]: Integration Interval in the CFX-Pre User's Guide and Case 3: Blade Flutter in the CFX-Solver Modeling Guide.

EFFICIENCY

Overall device efficiency can be monitored in CFX-Solver Manager, and the values are based on mass average field efficiency at the selected outlet boundary condition. Additionally, if requested in the solver, it is possible to monitor "Isentropic Compression", "Polytropic Compression", "Isentropic Expansion" and "Polytropic Expansion" efficiencies. For further details, see Isentropic Efficiency and Total Enthalpy in the CFX-Solver Modeling Guide. Note that in order to monitor the device efficiency, the Efficiency Output Check Box must be selected, according to Efficiency Output Check Box in the CFX-Pre User's Guide.

FLOW

The flows listed in the CFX-Solver Manager are the absolute amounts of a variable transported through a boundary condition. For example, the flow for the continuity (P-Mass) equation is the mass flow of a particular phase through the boundary condition. The flow for the energy (H-Energy) equation is the energy flow per unit time through the boundary condition.

FORCE or MOMENT

The pressure and viscous moments are related to the pressure and viscous forces calculated at the wall. For details, see Calculated Wall Forces and Moments and Monitor Forces: Option in the CFX-Pre User's Guide.

IMBALANCE

Percent imbalance is the normalized sum of the flows for a given equation on a particular domain. The absolute flow is normalized by the maximum flow, calculated by looking at flows on all domains for that particular equation.

NEG ACCUMULATION

Negative accumulation is the transient term contribution to the balance equation. For details, see the description for "IMBALANCE" in this table.

PARTICLE

If particles exist in your simulation, this category includes monitor particle forces and moments on walls, particle source change rates, total particle mass flow rates at boundaries or the particle injection region, and particle penetration variables.

RADIOMETER

A radiometer is a user-defined point in space that monitors irradiation heat flux (not incident radiation) at the required location. For details, see Radiometers in the CFX-Solver Modeling Guide. This variable can be used for specific monitoring of radiation calculations with ray tracing.

RESIDUAL

For details, see Residual Plotting.

RIGID BODY

A rigid body is a solid object that moves through a fluid without itself deforming. For details, see Monitor Plots related to Rigid Bodies in the CFX-Solver Modeling Guide. An automatically created rigid body monitor point must be selected from the Monitors menu in order to view the measurement of displacement of body on a global coordinate frame. Note that all of the plot line variables pertaining to a rigid body are with respect to the global coordinate frame.

SOURCE

You can monitor source terms either over an entire domain, or at particular regions of a domain, such as points, boundaries and subdomains. If you have set up user-defined source terms, the monitored region can also be user-defined.

Depending on which models are used, some source terms are automatically computed and monitored over entire domains by the solver. For example, source terms that represent the production and dissipation of turbulence are calculated as part of the turbulent kinetic energy equation.

TIMESTEP

Under the TIMESTEP branch of the tree on the Plot Lines tab, the available variables are: Accumulated Timestep, Current Timestep, and Time.

CFX-Solver Manager uses Current Timestep to show the step the solver is currently on for the active run while the solver works to achieve convergence in a given simulation.

CFX-Solver Manager uses Time to show the elapsed physical time of the simulation in the solution units. For details on specifying solution units, see Setting the Solution Units in the CFX-Pre User's Guide.

USER POINT

If monitor points have been created, a USER POINT category is available. This can be expanded to select the monitor points to plot. For details, see Monitor Tab in the CFX-Pre User's Guide.