Your First Simulation¶

In this tutorial you will create a minimal DWSIM simulation in the Classic UI: a single water stream at a known temperature and pressure. You will learn how to set up a new chemical process model, add compounds, choose a property package, and read calculated properties from the stream.

What you will learn

How to create a new chemical process model
How to navigate the Simulation Configuration Wizard
How to add compounds and select a property package
How to define a material stream with temperature, pressure, and flow rate
How to enable the calculator and read calculated properties

Prerequisites

DWSIM v10.0+ installed (Classic UI on Windows)
No prior simulation experience required

Process Overview¶

This is the simplest possible simulation: a single pure-water stream at 25 °C and 1 atm. After solving, DWSIM calculates all thermodynamic properties (density, enthalpy, entropy, heat capacity, etc.) using the IAPWS-IF97 Steam Tables model.

There is no process flow diagram here because we are working with a single stream. Think of it as the "Hello World" of process simulation.

Key Design Parameters¶

Parameter	Value	Unit
Compound	Water	-
Property Package	Steam Tables (IAPWS-IF97)	-
Temperature	298.15 (25 °C)	K
Pressure	101325 (1 atm)	Pa
Mass flow	1.0	kg/s

Step-by-Step in the Classic UI¶

1. Create a new chemical process model¶

Open DWSIM. From the home screen, click the New Steady-State Simulation button on the toolbar, or use the menu: File > New Chemical Process Model.

The Simulation Configuration Wizard opens automatically.

Simulation Configuration Wizard - Introduction

Click Next to advance.

2. Add the Water compound¶

You are now on the Compounds page. Type Water in the search box at the top. The grid below filters to show matching compounds from the available databases (DWSIM, ChemSep, CoolProp, Biodiesel, ChEDL, Electrolytes).

Find the row for Water (CAS 7732-18-5, source: ChemSep or DWSIM) and check the "Added" box on the left side of the row.

Adding Water as a compound

Click Next. (If the wizard shows a Reaction Finder page, just click Next again - we are not adding any reactions.)

3. Select the property package¶

On the Property Packages page, click the "Select a Property Package from the list to add it to the simulation" dropdown and choose Steam Tables (IAPWS-IF97). The package appears in the Added Property Packages grid below.

Selecting Steam Tables property package

Why Steam Tables?

Steam Tables (IAPWS-IF97) is the international reference correlation for water and steam, with accuracy within 0.01% of experimental data. For pure-water systems, it is always the right choice.

Leave the Phase Equilibria option as "Leave as default (SVLLE)" and click Next.

4. Accept the remaining wizard pages¶

Click Next through the Behavior page (defaults are fine for now) and the Unit System page (SI is selected by default).

On the last page, click Finish. The wizard closes and the empty flowsheet canvas appears.

Empty flowsheet canvas

5. Insert a Material Stream¶

From the Object Palette on the side, drag a Material Stream icon onto the flowsheet canvas. Alternatively, use the menu: Insert > Flowsheet Object and select Material Stream from the list.

DWSIM gives the new stream a default name like MSTR-001. Right-click it and choose Rename if you want a friendlier name (e.g., Water-1).

Material Stream added to the flowsheet

6. Enter the stream specifications¶

Double-click the stream to open the Object Editor. In the Input Data / Properties section, enter the following:

Temperature: 298.15 K (or type 25 and switch the unit dropdown to °C)
Pressure: 101325 Pa (or type 1 and switch the unit dropdown to atm)
Mass Flow: 1 kg/s

Press Enter after each value to commit the change. In the Composition section, set Water's mole fraction to 1.0 (or normalize to 100%).

Stream specifications entered

7. Enable the calculator and solve¶

On the toolbar, make sure the Flowsheet Calculator Active (F6) toggle is ON (highlighted). Then click the Solve button.

The stream object's icon turns green to indicate successful calculation.

Stream solved successfully

8. View the results¶

Click the stream to open its editor, or check the Material Streams panel in the main window. You will see all calculated properties: density, enthalpy, entropy, viscosity, vapor fraction, etc.

Stream calculated properties

Results and Validation¶

Property	Expected Value	Unit
Temperature	298.15	K
Pressure	101325	Pa
Density	~997.0	kg/m³
Vapor fraction	0.0 (liquid)	-
Mass flow	1.0	kg/s

Expected results

The stream should be in the liquid phase (vapor fraction = 0) with a density close to 997 kg/m³, matching the well-known density of liquid water at 25 °C and 1 atm.

Understanding the Results¶

At 25 °C and 1 atm, water is well below its boiling point (100 °C at 1 atm), so the flash calculation correctly identifies it as a compressed liquid. The density of ~997 kg/m³ matches the NIST reference value for liquid water at these conditions.

The IAPWS-IF97 Steam Tables model is a correlation-based formulation specifically developed for water/steam systems. It provides very high accuracy (within 0.01% of experimental data) for pure water across a wide range of temperatures and pressures.

Automating This Tutorial¶

The same simulation can be built programmatically for batch automation, AI-assisted workflows, or integration with other tools.

Files in this repository

Python script: examples/beginner/01_first_simulation.py

FluentAPI (Python)MCP Server (JSON-RPC)LLM Prompt

from DWSIM.Automation.FluentAPI import Flowsheet, PropertyPackages, Q

fs = (Flowsheet.Create("MyFirstSimulation")
      .WithCompound("Water")
      .WithPropertyPackage(PropertyPackages.SteamTables))

stream = (fs.AddMaterialStream("Water-1")
          .At(Q.Kelvin(298.15), Q.Pascal(101325.0))
          .WithMassFlow(Q.KgPerSecond(1.0)))

fs.Solve()

print(f"Temperature     = {stream.TemperatureK:.2f} K")
print(f"Pressure        = {stream.PressurePa:.0f} Pa")
print(f"Density         = {stream.DensityKgPerM3:.2f} kg/m3")
print(f"Vapor fraction  = {stream.VaporFraction:.4f}")

{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{
  "name":"dwsim.flowsheet.create",
  "arguments":{"name":"MyFirstSimulation"}
}}

{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{
  "name":"dwsim.thermo.add_compounds",
  "arguments":{"flowsheet_id":"<ID>","names":["Water"]}
}}

{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{
  "name":"dwsim.thermo.set_property_package",
  "arguments":{"flowsheet_id":"<ID>","name":"SteamTables"}
}}

{"jsonrpc":"2.0","id":4,"method":"tools/call","params":{
  "name":"dwsim.stream.add_material",
  "arguments":{
    "flowsheet_id":"<ID>","name":"Water-1",
    "temperature_K":298.15,"pressure_Pa":101325,
    "mass_flow_kg_s":1.0,"composition":{"Water":1.0}
  }
}}

{"jsonrpc":"2.0","id":5,"method":"tools/call","params":{
  "name":"dwsim.solve.run",
  "arguments":{"flowsheet_id":"<ID>"}
}}

Output may vary

Results depend on the LLM's reasoning quality and tool-use accuracy. Always verify the simulation matches your intent before relying on the numbers.

Use DWSIM (via the MCP server) to build the following simulation:

- Create a flowsheet called "MyFirstSimulation"
- Add Water as the only compound; set the property package to "SteamTables"
- Add a material stream named "Water-1" at 298.15 K and 101325 Pa
  with a mass flow of 1.0 kg/s
- Solve the flowsheet
- Report the calculated temperature (K), pressure (Pa), density (kg/m³)
  and vapor fraction of the stream

Exercises

Change the temperature to 373.15 K (100 °C) by editing the stream and pressing F6 → Solve again. Observe the vapor fraction. What happens?
Increase the pressure to 10 atm (1013250 Pa) at 373.15 K. Does the water remain liquid?
Save your simulation: File > Save → choose a .dwxmz file. Then close it and re-open it via File > Open File.

Next Steps¶

Now that you can create a simulation and inspect stream properties, move on to Mixer Basics to learn how to connect streams to a unit operation.