# Heat Flux in 1D-Heat Conduction

**URL:** <https://discourse.opengeosys.org/t/heat-flux-in-1d-heat-conduction/1424>\
**Category:** Help & Support\
**Created:** [June 18, 2024, 2:04pm UTC](https://discourse.opengeosys.org/t/heat-flux-in-1d-heat-conduction/1424 "2024-06-18T14:04:46Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![M\_Jaeschke](https://discourse.opengeosys.org/letter_avatar_proxy/v4/letter/m/258eb7/32.png) [@M\_Jaeschke](https://discourse.opengeosys.org/u/M_Jaeschke)\
**Post date:** [June 18, 2024, 2:04pm UTC](https://discourse.opengeosys.org/t/heat-flux-in-1d-heat-conduction/1424/1 "2024-06-18T14:04:46Z")

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Dear OGS-Community,

I want to simulate the temperature distribution in the subsurface at different horizontal heights, to get the undisturbed temperature field. For this problem a line in vertical direction should be enough. So I define a temperature curve as Dirichlet BC for the top point and a terrestrial heat flux for the bottom point as Neumann BC. The simulation runs, but the results look not as expected. I want the heat flux only in the z-direction, but it seems that the heat flux go away to the x- and y- direction. Is it possible, to define that the x- and y- component of the heat flux should be zero at every point?

 ![HeatFlow_1D_Heat_Conduction](https://discourse.opengeosys.org/uploads/default/original/2X/8/842d5586a7b55d60cf42e6595fa6db057c1d17b2.png)

Another way to solve the problem is the usage of a large domain with 2D `axially_symmetric` mesh, but this is not so elegant and computationally fast as solving only on a line.

The input data for the line example can be download here: [GigaMove](https://gigamove.rwth-aachen.de/de/download/83ee262432505f77d96bb69677d0db03)

Best regards,  
Max

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<div class="post-metadata">

**Author:** ![M\_Jaeschke](https://discourse.opengeosys.org/letter_avatar_proxy/v4/letter/m/258eb7/32.png) [@M\_Jaeschke](https://discourse.opengeosys.org/u/M_Jaeschke)\
**Post date:** [June 19, 2024, 5:32am UTC](https://discourse.opengeosys.org/t/heat-flux-in-1d-heat-conduction/1424/2 "2024-06-19T05:32:58Z")

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I found my error in the meantime, I was a bit confused yesterday about the output of `heat_flux` and `HeatFlowRate`. Sorry if someone has thought about my problem.

My expected result is to get a geothermal gradient \Delta T according to \dot{q}=\lambda \cdot \Delta T. My initial simulation above runs only for 25 years and the equilibrium is not reached in this time - with a simulation time of 100 years it looks better, but with the currently initial condition its need longer then the 100 years to reach the equilibrium.