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Incorporating dip angle in meshmaker

Hello,

I am trying to model a gently dipping aquifer, and am setting up the grid using the online meshmaker utility. The input field called "Angle between Y-axis and the horizontal" is meant to help users incorporate a dip angle, correct? What is the intended unit on this?

Assuming it is supposed to be degrees, I set this value to -0.7, but this didn't produce the result I intended. Across my 15 km x 15 km grid, a dip angle of -0.7 degrees should cause a decrease in the z-coordinate of ~183 m, but the z coordinates don't change among any of the lateral locations.

Can anyone help me to incorporate my intended dip angle correctly?

Thank you very much for your time,

Michelle

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  • Hey Michelle,

    The dip angle (written in degrees) will be introduced in the BETAX listings in the CONNE block. It adds a component of the gravitational vector in what was the horizontal direction and reduce the gravitational component of the vertical direction by a corresponding amount. The coordinates listed in the ELEME block are there for post-processing purposes only and have no bearing on the simulation results. If you'd like the dip angle to be reflected in the coordinate listings of your outputs, you'll need to calculate those changes directly in your post-processor of choice before plotting the results.

    Thanks!
    - Mikey

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  • Thank you Mikey!

    I guess this means that, to achieve my intended model dimensions and discretizations, I will need to adjust the lengths in the Y-direction (the direction of dip) and Z-direction (vertical) according to the dip angle? That is, if I want elements that are 100 m long in the Y-direction when looking from directly above, then the dY length I should input will actually be 100/cos(dip angle). And likewise, if I want the element thickness (in the vertical direction) to be 42 m, then the dZ length I should input will be 42/cos(dip angle)?

    Please let me know if I'm mistaken about that.

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  • Michelle, I think that's right. Or, if you can get away with it, you can simply recognize that your line of sight is aligned with the dipping formation. However, if you want or need your Y direction to be truly horizontal, then you may need to adjust your cell dimension like you suggest or add additional cells in each direction if you need your full domain to span the same length as you originally intended.

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    • Mikey Hannon great, thank you again! I am making a model that represents a field site with precise well locations, so I want to make sure that I'm able to easily pick out elements that represent the correct locations of those wells. Therefore, I used the "projection" calculations described above so that the domain will have round-number discretization sizes in plan-view and vertical directions.

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