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Theoretical guide for IDA Tunnel

Last modified by Walter Fornari on 2026/08/26 10:24

Theoretical reference for IDA Tunnel

About this document

This document describes the mathematical models that are the basis of IDA Tunnel. All models have been described in terms of equations in the modeling language Modelica. Several models are included as source code in the standard delivery and the remainder is available by separate agreement with EQUA. A reader with some familiarity of Modelica should easily be able to find the correspondence between the mathematics presented here and the corresponding source code. Names of variables and parameters are not necessarily the same in the source code and in this document. In the source code we try to use self explanatory and established names while in the documentation it is more convenient to use a concise notation. To aid the reader the names used in the source code are also given (at the right margin) for most of the variables and parameters together with unit if not the same as the SI-unit used in the mathematical documentation. The solution of given equations is handled by IDA Simulation Environment and the details of this process is not covered in this document.

IDA Road Tunnel Ventilation (IDA RTV), which is a subset of IDA Tunnel, has the following limitations. Models with explicit train traffic (rail section, platform) are not included. Not all air quality measures are computed. The air humidity is set zero. Superposition of temperature fields caused by neighboring tunnels, ground surface and known boundaries is not available.

 Contents

About this document

The models

    Calculation of airflow

        Rail tunnel section (RailSection)

        Road tunnel section (RoadSection)

        Platform (Platform)

        Plenum (Plenum)

        Tunnel entry (Entry)

        Tunnel portal (Portal)

        Recirculation (Recirc)

        Tunnel junction (Branch)

        Supply or exhaust fan to ambient (FanDuct)

        Leak (Leak)

        Given volume airflow (VFGiven)

        Filter (Filter)

        Damper (Damper)

        Passage (Passage)

        Axial fan (AxialFan)

        Saccardo nozzle (SaccarNoz)

    Calculation of heat flow

        Tunnel section heat balance (RailSection, RoadSection)

        Platform (Platform)

        Plenum (Plenum)

        Wall

        Heater (Heater)

        Fire model

        Train heat model

        Train compartment heating and air conditioning

        Cooling pipes

    Air quality

        Age of air

        CO2 content

        Extinction coefficient

        Humidity fraction

        Particle content

        CO, NO2 and HC contents

Other models

        Tunnel water flow model: condensation, evaporation, seepage and drainage

        Critical velocity

        Mold growth index

        Ice build-up

        Train motion

        Fire throttling effect

        Back Layering length for tunnel fire under longitudinal ventilation

        Inventory of models

References

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