# OpenFOAM function object crashes at the end of the simulation due to setting deltaT to zero

**URL:** <https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957>\
**Category:** Official adapters and tutorials\
**Tags:** openfoam, adapters\
**Created:** [June 14, 2026, 2:45pm UTC](https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957 "2026-06-14T14:45:46Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![marhatom](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/marhatom/32/1981_2.png) [@marhatom](https://precice.discourse.group/u/marhatom)\
**Post date:** [June 14, 2026, 2:45pm UTC](https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957/1 "2026-06-14T14:45:46Z")

</div>

Hello

I am using OpenFOAM-adapter-v1.3.1. I think there is an issue with the adapter at the end of the OpenFOAM simulation when the simulation (coupling) finishes and the function objects get triggered one last time.

```
---[precice] [0m Reached end at: final time-window: 5000, final time: 0.5
---[preciceAdapter] The coupling completed.
---[precice] [0m Close communication channels
---[preciceAdapter] The simulation was ended by preCICE. Calling the end() methods of any functionObject explicitly.
---[preciceAdapter] Great that you are using the OpenFOAM-preCICE adapter! Next to the preCICE library and any other components, please also cite this adapter. Find how on https://precice.org/adapter-openfoam-overview.html.
forces vocalFoldForces write:
    Sum of forces
        Total : (0.03076961 -0.0007374726 -3.863188e-06)
        ...

```

I am using fixed timestep, so the following function gets called by the adapter

```
 // Adjust the timestep, if it is fixed
    if (!adjustableTimestep_)
    {
        adjustSolverTimeStepAndReadData(); // <-----
    }

    // If the coupling is not going to continue, tear down everything
    // and stop the simulation.
    if (!isCouplingOngoing())
    {
        adapterInfo("The coupling completed.", "info");
        ...

```

In the `adjustSolverTimeStepAndReadData()` function the timestep gets set zero

```
else if (timestepSolverDetermined - precice_->getMaxTimeStepSize() > tolerance)
    {
        // In the last time-step, we adjust to dt = 0, but we don't need to trigger the warning here
        ...
        timestepSolver_ = precice_->getMaxTimeStepSize();
    }
const_cast<Time&>(runTime_).setDeltaT(timestepSolver_, false); 

```

Which I assume is fine for most of the function objects, but Curle function object calls `fvc::ddt(p)` which uses deltaT in denominator and as a result causes a crash.

```
...
surfaceFieldValue volumeFlowRateOutlet write:
    total faces = 1128
    total area = 0.0001

    sumMag(outlet) of phi = 0.000196024

[4] [stack trace]
[4] =============
[1] [stack trace]
[1] =============
...
==== backtrace (tid: 14466) ====
 0 0x000000000003fc30 __GI___ sigaction() :0
 1 0x000000000008d02c __pthread_kill_implementation() ???:0
 2 0x000000000003fb86 __GI_raise() :0
 3 0x000000000003fc30 __GI___ sigaction() :0
 4 0x0000000001f43ba4 Foam::operator/<double>() ???:0
 5 0x00000000006e5bbc Foam::operator/() ???:0
 6 0x0000000001c74c06 Foam::fv::backwardDdtScheme<double>::fvcDdt() ???:0
 7 0x0000000001d14162 Foam::fvc::ddt<double>() ???:0
 8 0x000000000063e958 Foam::functionObjects::Curle::execute() ???:0
 9 0x00000000006b670f Foam::functionObjects::timeControl::execute() ???:0
10 0x00000000006a9497 Foam::functionObjectList::execute() ???:0
11 0x00000000006c8309 Foam::Time::run() ???:0
12 0x000000000042d44f main() ???:0
13 0x000000000002a610 __libc_start_call_main() ???:0
14 0x000000000002a6c0 __libc_start_main_alias_2() :0
15 0x0000000000430e45 _start() ???:0

```

---

<div class="post-metadata">

**Author:** ![Makis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/makis/32/25_2.png) [@Makis](https://precice.discourse.group/u/Makis)\
**Post date:** [June 15, 2026, 8:39am UTC](https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957/2 "2026-06-15T08:39:11Z")

</div>

@marhatom which preCICE version are you using? There were issues with time step sizes reaching zero in some releases.

---

<div class="post-metadata">

**Author:** ![marhatom](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/marhatom/32/1981_2.png) [@marhatom](https://precice.discourse.group/u/marhatom)\
**Post date:** [June 15, 2026, 3:08pm UTC](https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957/3 "2026-06-15T15:08:45Z")

</div>

I am using preCICE version 3.4.0

---

<div class="post-metadata">

**Author:** ![fsimonis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/fsimonis/32/6_2.png) [@fsimonis](https://precice.discourse.group/u/fsimonis)\
**Post date:** [July 30, 2026, 10:27am UTC](https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957/4 "2026-07-30T10:27:57Z")

</div>

> [@marhatom](#):
>
> Which I assume is fine for most of the function objects, but Curle function object calls `fvc::ddt(p)` which uses deltaT in denominator and as a result causes a crash.

@Makis this sounds more like this `Curle function` is called after the last time step, expects the fixed time step, but finds the `0`, set by preCICE and fails.

---

<div class="post-metadata">

**Author:** ![Makis](https://yyz2.discourse-cdn.com/free1/user_avatar/precice.discourse.group/makis/32/25_2.png) [@Makis](https://precice.discourse.group/u/Makis)\
**Post date:** [August 17, 2026, 10:45am UTC](https://precice.discourse.group/t/openfoam-function-object-crashes-at-the-end-of-the-simulation-due-to-setting-deltat-to-zero/2957/5 "2026-08-17T10:45:58Z")

</div>

The first time reading through this (too fast), I did not realize this was involving [another function object that needs the `dt`](https://doc.openfoam.com/2306/tools/post-processing/function-objects/field/Curle/). We never considered interoperability with such function objects that consume the `dt`, so this is very much a blind spot.

I opened an issue and I will try to address it in the next days: [Setting the time step size at the end of the simulation · Issue #415 · precice/openfoam-adapter · GitHub](https://github.com/precice/openfoam-adapter/issues/415)

@marhatom any minimal working example or anything else to add since you first opened this thread?