Fluid Modeling Capabilities

Yes. All FluidFlow modules include heat transfer functionality as standard. This feature allows you to perform pipe heat loss calculations while accounting for local wind speed, surface emissivity, and ambient temperature.

The software includes a standard library of pipe insulation materials from which you can select the required thickness for each pipe. Convection, conduction, and radiation losses are calculated automatically.

When performing heat loss calculations, engineers can either enter a U value or let the software calculate this parameter automatically.

The software also allows engineers to analyze the effect of a fixed temperature change or energy transfer rate across pipes or fittings, as well as calculate heat transfer in buried pipes. FluidFlow maintains a complete energy balance throughout all piping systems.

Yes. FluidFlow fully supports closed-loop configurations. For guidance on modeling these systems, refer to the document below.

Modeling Closed Loop Systems in FluidFlow

Yes. Elevation data can be set at each node, with automatic calculation of gravitational head contribution to system pressure. This applies to all flow systems.

Yes. The Slurry module allows you to choose from the following non-Newtonian viscosity models:

Engineers can create a new non-Newtonian fluid by either entering the shear rate vs shear stress relationship or directly defining the fluid viscosity constants. This information is typically available from fluid rheology data.

Yes. Users can choose from a total of eight correlations when modelling settling slurry systems. When developing the model, the software will enunciate warning messages to assist the engineer in developing an efficient system design. This includes messages identifying the risk of saltation or pipe blockage.

FluidFlow includes three correlation options for calculating deposition velocity and five options for analyzing the pump performance de-rating.

FluidFlow offers eight two-phase correlation options to choose from. You can configure this via Options | Calculation | Two Phase.

When selecting the Whalley Criteria option, the software automatically evaluates the fluid physical properties in your model and applies the most appropriate correlation (from three available) based on specific criteria including mass flux and viscosity.

Note that the software automatically generates a flow pattern map for each pipe in two-phase flow systems, which you can view in the Charts tab of the Data Palette.

FluidFlow does not currently utilize interacting VLE data (K values, activity coefficients, fugacities, etc.) in flow calculations. For multi-component chemical mixtures with phase changes, the software makes estimations of vapor phase composition based on ideality. The software may not be suitable for systems with many components changing phase, though it may work with simplifying assumptions. FluidFlow is primarily designed for optimizing flow systems rather than functioning as a standalone process simulator.

Additionally, the software cannot model mass transfer between phases due to gas solubility, such as producing hydrochloric acid from mixing hydrogen chloride gas and water.

Can FluidFlow detect choked flow conditions?

Yes. FluidFlow automatically detects choked flow conditions and limits the mass flow rate accordingly. Choked flow can occur in two situations: when the flow path experiences a change in cross-sectional area, or when flow exits a pipe into a vessel or atmosphere. The software detects both conditions and displays a warning message indicating the presence or likelihood of choked flow.

When choked flow occurs at a change in cross-sectional area (such as at a valve, orifice plate, or pipe reducer), the warning message appears as follows:

When end-point choking occurs in a pipe, the warning appears as follows:

Yes. FluidFlow includes sprinkler and fire hydrant nodes among its components, which come with a default database. Additional sprinklers can be added to the database by either entering a single nominal K value or entering the flow vs pressure loss relationship. Similarly, additional hydrants can be added by entering either a single K value or a pressure loss relationship of % open vs Kv/Cv.

When defining either of these items using a pressure loss relationship, FluidFlow automatically generates the curve fit.

Yes, however, FluidFlow requires separate models for each fluid stream in a heat exchanger.
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For example, when modeling a heat exchanger, you would create one model for the tube side (e.g., ethanol at 45°C) and another separate model for the shell side (e.g., water at 15°C). You can then use the calculated results from one model as design inputs for the other model.

The Max Deposition Velocity is the deposition velocity at critical concentration, providing a reference point from which stationary deposition velocity can be calculated at any concentration. The Cvd Deposition Velocity is the deposition velocity at the specific concentration defined for your system and will vary based on slurry concentration.

Best practice suggests designing for velocities 30% higher than these values to prevent particle settling while reducing pipe wear and energy costs. You can apply engineering judgment based on your system knowledge when evaluating these calculated values.

The Chart tab on the Data Palette provides details of duty points on the system curve for each pipe for comparison.

The image below illustrates the typical slurry flow regimes and provides guidance on interpreting FluidFlow results.

Yes. FluidFlow offers multiple methods for modeling slurry systems in inclined pipes. The WASC (Wilson-Addie-Sellgren-Clift), Vsm, V50, and 4CM methods can be used as they inherently account for pipe inclination.

For angles between -20 and 80 degrees, FluidFlow allows application of inclination corrections. Outside this range, the software applies the modified Worster & Denny method to account for solids effects in vertical pipes.

For detailed information on slurry transport in inclined pipes, refer to "Slurry Transport Using Centrifugal Pumps" by Wilson, Addie, Sellgren, and Clift.

Yes. FluidFlow can model ducted ventilation systems. When placing a "Steel Pipe or Duct" on the flowsheet, you can set the duct as either circular or rectangular using the Geometry field in the Input Editor. You can also set "Use Database Size" to "No" to specify custom dimensions for your ducts.

A common approach is to fix the flow rate at each outlet boundary, specifying the required demands at each user point.

Stagnation Pressure is the sum of the Velocity Pressure and Static Pressure.

Generally, all pressure-type boundary conditions should be defined in terms of stagnation pressure. This works especially well for large storage tanks or atmospheric boundaries where volume associated with a given pressure remains stable regardless of flow conditions. Since these boundaries have zero velocity, stagnation pressure is the appropriate parameter to use.

When the Fluid Type is set to Two Phase, you must enter a Vapor Quality value between 0 and 1 (where 0 represents 0% vapor and 1 represents 100% vapor). For example, a quality of 0.2604 represents 26.04% vapor and 73.96% liquid. The software automatically calculates the fluid temperature based on this quality value. For systems with inlet quality of 0 (100% liquid), it's usually better to model as a liquid flow system with defined pressure and temperature. Similarly, for inlet quality of 1 (100% gas), modeling as a gas flow system is recommended. For near-saturated conditions, you can use slightly adjusted values (e.g., 0.05 for mostly liquid or 0.95 for mostly vapor) to initiate two-phase flow conditions.

In the FluidFlow database, "steam" is locked in the gas phase regardless of temperature and pressure conditions. This feature was added based on user requests for modeling steam in mixtures. If you need to model water that could potentially exist in liquid, gas, or two-phase states, use the "water" fluid option instead.

Yes. FluidFlow provides saltation/blockage warnings when a horizontal pipe has slurry velocity below the maximum deposition velocity. The software uses maximum deposition velocity rather than the actual deposition velocity at the current concentration, as this provides a safety margin to account for localized concentration variations and operational changes over time. This is considered best practice to cover all potential concentration scenarios.

For sloping and vertical pipes, blocking generally does not occur, and FluidFlow does not issue blockage warnings in these cases, as deposition velocity equations only apply to horizontal pipes.

Yes. FluidFlow allows you to create template files for common components like pump stations and valve stations. These templates can be saved and inserted into any model, significantly accelerating your design process and ensuring consistency across projects.

See Creating Flowsheet Templates for a quick tutorial.

Yes, FluidFlow allows you to swap pipe materials in a model. Here's how to do it:

Important Note: Different pipe materials have different data sets (diameters, roughness values, etc.). When changing materials, default values for the new material will be applied. You'll need to verify and adjust each pipe to ensure it has the required diameter and specifications after the material swap.

Yes. To isolate sections of a model, select the relevant pipes and fittings and set their Status to "Off or Closed" in the Input Editor. When you recalculate your model, you'll see that no flow occurs in these sections.

Yes. FluidFlow allows you to model gas systems with fluctuating conditions by setting demand/supply points to ON/OFF status. This lets you simulate points coming online or going offline throughout your system. You can also adjust flow rates or pressures at any location in the model. For more advanced applications, you can automate these changes over time using the Scripting Module after developing a baseline system model.

FluidFlow does not support modeling expansion tanks in-line within a system because this involves dynamic scenarios with fluctuating pressure and expansion, while FluidFlow is designed for solving static system conditions.

For closed-loop systems where expansion tanks are commonly used, you only need to include a "Reservoir" node in your model. This node is found in the Boundaries tab of the Component Palette and allows you to specify the fluid's pressure and temperature for your model.

Vent lines are typically modeled using a known pressure boundary to represent the inlet, with either a known pressure boundary or open pipe node at the outlet.

The key difference between these outlet options is that an open pipe node includes an exit loss (K Value = 1.0).

FluidFlow doesn't have a dedicated steam trap node; however, you can model steam/condensate systems and configure the model to solve with or without steam traps. To access these options, navigate to: Options | Calculation | Gas.

The image below illustrates how to model a spray bar or sparger arrangement. It shows several vertical 200 mm pipe sections, each with an 8 mm "Inside Diameter".

FluidFlow doesn't consider tank volume. When using a tank/reservoir node, the software only accounts for the surface pressure defined at the tank, the liquid level, and the pipe or branch connection height from the base of the tank.

To set the connection height, select the "Connections" row on the Input Editor.

The solution methods of Moller and TAPPI are recommended for use in specific ranges: 0.9-6% (Moller) and 2-6% (TAPPI). While the solver will calculate models outside these ranges, results may lose accuracy, and a warning message will appear. When changing the wt% oven dry concentration value at an inlet boundary node, ensure you click in another field afterward to complete the data entry before calculating the model.

To customize your preferred component default settings, select Options → Environment → Component Defaults, or press F4 on your keyboard. This opens the "Component Defaults" dialog where you can modify your default settings as needed.

There are no reliable correlations in the public domain for predicting two-phase choked flow conditions. FluidFlow solves the conservation of mass, energy, and momentum equations, and if the solution results in negative static pressure—which is physically impossible—the software displays a warning that may indicate potential choked flow conditions.

Stagnation pressure (also called total pressure) is the sum of static pressure and velocity pressure. It represents the pressure exerted by a fluid when brought to rest. In measurement terms, this is the pressure reading obtained from a pitot tube-type gauge where pressure is measured at the pipe's center, a point where friction loss is zero and velocity is at a maximum.

Static pressure is the pressure exerted by a fluid at rest. In measurement terms, this is the pressure reading obtained from a gauge whose measurement is taken at the pipe wall, a point where fluid velocity is zero.

Velocity pressure represents the kinetic energy of the fluid due to its motion.

In the FluidFlow sample below:

ALL physical properties for a new fluid must be defined in the database for it to be available in models. If any property is left as "undefined" (such as viscosity), the fluid won't appear when you try to assign it to a Known Pressure, Reservoir, or Known Flow Boundary node.

Once all properties are defined, the appropriate light bulb indicator will illuminate, indicating the fluid is available for use.

For detailed guidance on defining new fluids, refer to How to Enter Input Data.

When a branch connection of a tee junction is turned OFF, the straight section typically experiences minimal friction loss compared to other system losses. Different calculation methods handle this scenario differently:

These differences in calculation methods are consistent with the technical literature for each approach.

To include an equivalent length value for the straight section based on published literature, you can insert a Kf (L/D) node into the straight connection and enter your desired value using the Input Editor.

It depends on the type of outlet boundary you are using:

Yes. FluidFlow provides two methods for creating custom fluid mixtures:

1. Database Mixing

2. Flowsheet Mixing

When creating mixtures, please note that FluidFlow uses generalized equations of state and applies simple mixing rules (such as Plocker) to determine fluid behavior in the system.

The software does not account for property changes due to immiscibility or heat effects from fluid mixing. Additionally, any chemical reactions that might occur as fluids flow through the system are not considered in calculations.