Creating a BHE mesh (Borehole Heat Exchanger)

This example demonstrates how to use ogstools.meshlib.gmsh_meshing.gen_bhe_mesh to create a Borehole Heat Exchanger (BHE) mesh.

from pathlib import Path
from tempfile import mkdtemp

import pyvista as pv
from pyvista.plotting import Plotter

from ogstools.meshlib.gmsh_meshing import BHE, Groundwater, gen_bhe_mesh

Introduction

This example shows the general usage of ogstools.meshlib.gmsh_meshing.gen_bhe_mesh and how some of the parameters will effect the mesh. This section demonstrates the mesh generation with only three soil layers, groundwater flow in one layer and three BHE’s. However, this tool provides multiple soil layers, groundwater flow in multiple layers and multiple BHE’s. The mesh sizes provides good initial values for the most Heat-Transport-BHE simulations in OGS. They can also be set by the user, to customize the mesh. Feel free to try it out!

Create a simple prism mesh

Generate a customizable prism BHE mesh:

tmp_dir = Path(mkdtemp())
vtu_file = tmp_dir / "bhe_prism.vtu"
bhe_meshes = gen_bhe_mesh(
    length=150,
    width=100,
    layer=[50, 50, 50],
    groundwater=Groundwater(
        begin=-30, isolation_layer_id=1, flow_direction="+x"
    ),
    BHE_Array=[
        BHE(x=50, y=40, z_begin=-1, z_end=-60, borehole_radius=0.076),
        BHE(x=50, y=50, z_begin=-1, z_end=-60, borehole_radius=0.076),
        BHE(x=50, y=60, z_begin=-1, z_end=-60, borehole_radius=0.076),
    ],
    meshing_type="prism",
    out_name=vtu_file,
)

Load the domain mesh and all submeshes as well as extract the BHE lines:

mesh = pv.read(tmp_dir / bhe_meshes[0])
top_mesh = pv.read(tmp_dir / bhe_meshes[1])
bottom_mesh = pv.read(tmp_dir / bhe_meshes[2])
gw_mesh = pv.read(tmp_dir / bhe_meshes[3])
bhe_line = mesh.extract_cells_by_type(pv.CellType.LINE)

Visualize the mesh:

top_mesh = top_mesh.translate((0, 0, 10), inplace=False)
bottom_mesh = bottom_mesh.translate((0, 0, -10), inplace=False)
gw_mesh = gw_mesh.translate((-10, 0, 0), inplace=False)

p = Plotter()
p.add_mesh(mesh, style="wireframe", color="grey")
p.add_mesh(
    mesh.clip("x", bhe_line.center, crinkle=True),
    show_edges=True,
    scalars="MaterialIDs",
    cmap="Accent",
    categories=True,
    scalar_bar_args={"vertical": True, "n_labels": 2, "fmt": "%.0f"},
)
p.add_mesh(bhe_line, color="r", line_width=3)
p.add_mesh(top_mesh, show_edges=True)
p.add_mesh(bottom_mesh, show_edges=True)
p.add_mesh(gw_mesh, show_edges=True)
p.add_axes()
p.show()

Static Scene

Interactive Scene

Create a simple structured mesh

Generate a customizable structured BHE mesh:

tmp_dir = Path(mkdtemp())
vtu_file = tmp_dir / "bhe_structured.vtu"
bhe_meshes = gen_bhe_mesh(
    length=150,
    width=100,
    layer=[50, 50, 50],
    groundwater=Groundwater(
        begin=-30, isolation_layer_id=1, flow_direction="+x"
    ),
    BHE_Array=[
        BHE(x=50, y=40, z_begin=-1, z_end=-60, borehole_radius=0.076),
        BHE(x=50, y=50, z_begin=-1, z_end=-60, borehole_radius=0.076),
        BHE(x=50, y=60, z_begin=-1, z_end=-60, borehole_radius=0.076),
    ],
    meshing_type="structured",
    out_name=vtu_file,
)

Load the domain mesh and all submeshes as well as extract the BHE lines:

mesh = pv.read(tmp_dir / bhe_meshes[0])
top_mesh = pv.read(tmp_dir / bhe_meshes[1])
bottom_mesh = pv.read(tmp_dir / bhe_meshes[2])
gw_mesh = pv.read(tmp_dir / bhe_meshes[3])
bhe_line = mesh.extract_cells_by_type(pv.CellType.LINE)

Visualize the mesh:

top_mesh = top_mesh.translate((0, 0, 10), inplace=False)
bottom_mesh = bottom_mesh.translate((0, 0, -10), inplace=False)
gw_mesh = gw_mesh.translate((-10, 0, 0), inplace=False)

p = Plotter()
p.add_mesh(mesh, style="wireframe", color="grey")
p.add_mesh(
    mesh.clip("x", bhe_line.center, crinkle=True),
    show_edges=True,
    scalars="MaterialIDs",
    cmap="Accent",
    categories=True,
    scalar_bar_args={"vertical": True, "n_labels": 2, "fmt": "%.0f"},
)
p.add_mesh(bhe_line, color="r", line_width=3)
p.add_mesh(top_mesh, show_edges=True)
p.add_mesh(bottom_mesh, show_edges=True)
p.add_mesh(gw_mesh, show_edges=True)
p.add_axes()
p.show()

Static Scene

Interactive Scene

Create an advanced structured mesh

Generate a customizable structured BHE mesh with advanced mesh sizing options (using gmsh). To understand the specific behaviour of every mesh parameter, test each one after another.

vtu_file = tmp_dir / "bhe_structured_advanced.vtu"
bhe_meshes = gen_bhe_mesh(
    length=150,
    width=100,
    layer=[50, 50, 50],
    groundwater=Groundwater(-30, 1, "+x"),
    BHE_Array=[
        BHE(50, 40, -1, -60, 0.076),
        BHE(50, 50, -1, -60, 0.076),
        BHE(50, 60, -1, -60, 0.076),
    ],
    meshing_type="structured",
    target_z_size_coarse=10,  # default value 7.5
    target_z_size_fine=2,  # default value 1.5
    n_refinement_layers=1,  # default value 2
    dist_box_x=15,  # default value 10
    propagation=1.2,  # default value 1.1
    inner_mesh_size=8,  # default value 5
    outer_mesh_size=12,  # default value 10
    out_name=vtu_file,
)

Load the domain mesh and all submeshes as well as extract the BHE lines:

mesh = pv.read(tmp_dir / bhe_meshes[0])
top_mesh = pv.read(tmp_dir / bhe_meshes[1])
bottom_mesh = pv.read(tmp_dir / bhe_meshes[2])
gw_mesh = pv.read(tmp_dir / bhe_meshes[3])
bhe_line = mesh.extract_cells_by_type(pv.CellType.LINE)

Visualize the mesh:

top_mesh = top_mesh.translate((0, 0, 10), inplace=False)
bottom_mesh = bottom_mesh.translate((0, 0, -10), inplace=False)
gw_mesh = gw_mesh.translate((-10, 0, 0), inplace=False)

p = Plotter()
p.add_mesh(mesh, style="wireframe", color="grey")
p.add_mesh(
    mesh.clip("x", bhe_line.center, crinkle=True),
    show_edges=True,
    scalars="MaterialIDs",
    cmap="Accent",
    categories=True,
    scalar_bar_args={"vertical": True, "n_labels": 2, "fmt": "%.0f"},
)
p.add_mesh(bhe_line, color="r", line_width=3)
p.add_mesh(top_mesh, show_edges=True)
p.add_mesh(bottom_mesh, show_edges=True)
p.add_mesh(gw_mesh, show_edges=True)
p.add_axes()
p.show()

Static Scene

Interactive Scene