Inlet
Use the Inlet node to set the velocity, volumetric flow rate, or mass flow rate inlet conditions that describe the fluid flow condition at an inlet.
In most cases the inlet boundary conditions appear, some of them slightly modified, in the Outlet type as well. This means that there is nothing in the mathematical formulations to prevent a fluid from leaving the domain through boundaries where the Inlet type is specified.
Inlet Specification
Select a Specification for the inlet — Mass flow rate (the default), Velocity, Volumetric flow rate. Additionally, Pump and Reservoir options are available for the Pipe Flow interface.
•
For Mass flow rate, enter a value or expression for the Mass flow rate qm,0 (SI unit: kg/s). The default is 0 kg/s.
•
For Velocity, enter a value or expression for the Velocity u0 (SI unit: m/s). The default is 0 m/s.
•
For Volumetric flow rate, enter a value or expression for the Volumetric flow rate qv,0 (SI unit: m3/s). The default is 0 m3/s.
•
For Standard flow, SCCM, enter a value for standard cubic centimeters per minute. The standard pressure and standard temperature as well as mean molar mass are required as inputs as well. A standard cubic centimeter of gas is the amount of molecules occupying a cubic centimeter at a specified standard temperature and pressure, calculated by the ideal gas law. When used in the oil and gas industry, the standard is often 15 degrees C and 100 kPa, but there are many other slightly different standard conditions used in other circumstances. The inlet velocity calculation is done according to
•
For Pump, enter a value for the External pressure pext (SI unit: Pa) and define the relationship between the head and the volumetric flow rate— Pump curve data, or User defined.
Pump Curve Data
When Pump curve data is selected as the Pump curve, a table appears, in which the values of the Flow rate and the Head can be either specified or imported from a text file by clicking the Load from file button () under the table. The interpolation between points given in the table is defined using the Interpolation function type list in the Pump Curve Interpolation section. Units can be specified for the Flow rate and the Head in the Units section.
User Defined
With the User defined option, an expression for the Pump curve can be specified. The flow rate across the point where this boundary condition is applied is defined by phys_id.V0 where phys_id is the name (by default for pipe flow, phys_id is pfl). In order to avoid unexpected behavior, the function used for the pump curve returns the maximum of the user-defined function and 0.
•
For Reservoir, enter values for reservoir density and pressure. Select a Entrance type — Projecting (K = 1) (the default), Sharp edged (K = 0.5), Rounded (K = 0.05), or User- defined loss coefficient.