Your First Model

What you'll learn

Simulation workflow: write Modelica, simulate, and plot results
How to read a second-order ODE in Modelica syntax
How to interact with the simulation workbench

Welcome to Rumoca. In this tutorial you will write a Modelica model, simulate it, and explore the results — all in your browser. No install required.

We will start with the double integrator — the simplest second-order ODE. A constant acceleration a drives velocity v, which drives position x:

\frac{d x}{d t} \frac{d v}{d t} = v = a

Try it

The editor below contains a complete Modelica model. Click Simulate to run 5 seconds of integration. Toggle variables in the plot legend to explore the results.

What just happened?

Simulate — Rumoca parsed your Modelica source and integrated the ODE in your browser using WebAssembly. No server round-trip.
Plot — State trajectories are plotted over time. Position x grows quadratically; velocity v grows linearly.

Things to try

Change the acceleration a to -9.81 and re-simulate — you now have free-fall under gravity.
Give the ball an initial velocity by changing v(start = 0.0) to v(start = 5.0).
Increase the simulation time to see how the trajectories extend.

Mass-Spring-Damper →