Richard J.A.M. Stevens

Physics of Fluids · University of Twente

Publication 98 · Wind-farm flow

Evaluating the accuracy of the actuator line model against blade element momentum theory in uniform inflow

L. Liu, L. Franceschini, D.F. Oliveira, F.C.C. Galeazzo, B.S. Carmo, R.J.A.M. Stevens, Wind Energy 25 (6), 1046-1059 (2022).

Main finding

The paper provides a strong hierarchy: integrated coefficients, local loads, and wake/vortex fields have different resolution requirements. It does not provide one universal ALM resolution criterion.

Relative error of axial and tangential blade force along the blade for six grid resolutions
How to read the figure. Relative error of the axial (A) and tangential (B) force per unit span along the blade, against radial position, for six grid resolutions measured against the finest. The error is largest at the root and the tip and falls as resolution increases, but between a two-metre and a one-metre grid the local forces still differ by as much as 10%. Over that same range Figure 6 shows the integrated thrust and power coefficients agreeing to within 1%, so getting the total right does not mean the distribution is right. Open the full-resolution figure. Figure 5. L. Liu et al. (2022). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Matching integrated actuator-line loads does not guarantee accurate spanwise loading, turbulence, or wake-vortex structure.

Research context

Earlier coarse-grid work identifies projection-kernel bias, while wind-tunnel comparisons show that wake-model accuracy depends on the chosen metric. Subsequent tip-loading work adds a sampled-velocity correction, and yawed-vortex simulations examine structure beyond integrated loads.

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