{"id":"ca6903e1-95b5-4bd4-9c01-03c268532a7e","arxiv_id":"2501.10626","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":7.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":6,"one_line_summary":"Simulations of elongated grains on an incline reveal an S-shaped dependence of the Pouliquen flow-rule slope on particle aspect ratio, with plateaus below AR about 1.3 and above AR about 2.","lead":"This paper uses computer simulations to show that elongated grains change how granular avalanches flow: the flow-rule parameter stays flat until grains are about 1.3 times longer than wide, jumps sharply, and flattens again beyond twice as long. The resulting S-shaped curve could help model landslides and industrial flows of non-spherical particles.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The S-shaped β(AR) relation may be confounded with clump corrugation: Cx drops from 0.971 to 0.917 exactly over the sharp rise, and the paper's corrugation test only covers the plateau regime.","rationale":"The reader identified the k_omega plateau as the weakest assumption, focusing on the mechanistic explanation. That concern is real but secondary: the paper's own Section V concedes that neither k_omega nor the order parameter S shows a transition as sharp as β. The more load-bearing issue is upstream of the mechanism: the independent variable AR is confounded with the clump convexity Cx in the exact region where β changes sharply. The paper's Appendix A acknowledges corrugation as 'an additional frictional mechanism' and demonstrates its dynamical importance at AR=3, but does not control for the strong Cx variation between AR=1.3 and AR=1.5. Because the S-shape is the paper's central claim, and because the basal friction law Eq. (7) inherits the logistic fit Eq. (4), a confound at this level would invalidate the main contribution rather than merely weaken the interpretation. The proposed concrete test (smooth particles or constant-Cx clumps, plus targeted PAR3 variations at intermediate AR) would settle the question. The empirical data and fitting presented are internally consistent, and the comparison with literature endpoints is persuasive, so a full rejection is not warranted without this test. The verdict should remain CONDITIONAL, but with the condition explicitly on corrugation control rather than on the microscopic rotation story.","tokens_in":16526,"tokens_out":7112,"duration_ms":75320,"concrete_test":"Repeat the AR sweep with a smooth elongated shape representation (e.g., superellipsoids) or with clumps re-tuned to keep Cx constant near 0.92 across all AR values, and recompute β(AR). Alternatively, at minimum, run the existing clump model for AR=1.3, 1.4, and 1.5 with PAR3=7 and 9 (the parameter varied only for AR=3 in Fig. 8a) and check whether β at those intermediate AR values moves toward the AR≥2 plateau. If the sharp rise between AR=1.3 and AR=2.0 persists under constant corrugation, the S-shape is a genuine elongation effect; if it flattens or tracks the Cx variation, the reported S-shape is a corrugation artifact.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The central empirical claim is the S-shaped dependence of β on aspect ratio, but the particle shape control is not clean: clumped-sphere particles have a shape descriptor Cx (convexity) that varies systematically with AR. From Appendix A/Fig. 8(b), Cx = 1.000 (AR=1.0), 0.991 (AR=1.1), 0.989 (AR=1.2), 0.971 (AR=1.3), 0.948 (AR=1.4), 0.917 (AR=1.5), and remains 0.917 for AR=2.0, 2.5, 3.0. This pattern is almost a mirror image of the β-AR data: β is nearly flat for AR ≤ 1.3, rises sharply from 0.240 at AR=1.3 to 0.516 at AR=2.0, and then plateaus for AR ≥ 2. Thus the sharp transition in β coincides exactly with the drop in particle convexity/corrugation, while the two plateaus coincide with regimes of nearly constant Cx. The paper's own Appendix A (Fig. 8a) shows that increasing the number of spheres per clump at fixed AR=3 increases flow mobility, demonstrating that corrugation-level roughness has a dynamical effect. However, that sensitivity check is performed only in the second plateau regime (AR=3, Cx=0.917) and does not probe the transition region AR=1.3–1.5 where Cx changes most. Consequently, the reported S-shape may reflect clump discretization rather than elongation per se. This is a load-bearing concern because it threatens the empirical β-AR relation itself, not just the microscopic explanation.","agreement_with_reader":"disagree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper uses DEM simulations of clumped-sphere particles with aspect ratios AR from 1 to 3 to study dense granular flows down rough inclined planes. For each AR the authors extract h_stop(θ) curves and the Pouliquen scaling Fr versus h/h_stop, showing that the scaling holds individually for each AR but with a slope β that increases with AR in an S-shaped manner: a plateau for AR ≲ 1.3, a sharp rise between 1.3 and 2.0, and a second plateau beyond AR ≈ 2.0. They fit this trend with a four-parameter logistic function (Eq. 4) and combine it with Pouliquen's flow rule to propose a shape-dependent basal friction law (Eq. 7). Microscopic statistics of particle orientation (order parameter S, preferred angle αxz^p) and rotation (kω from the ω–γ̇ relation) are presented to explain the three-regime behavior.","tokens_in":16899,"tokens_out":5736,"duration_ms":56920,"significance":"The systematic sweep over aspect ratio connects the spherical-particle regime with the strongly non-spherical regime, and the suggestion that Pouliquen's scaling survives per AR but not across AR is a useful result for shallow-flow modeling of non-spherical grains. The study is carefully executed: it includes domain-size checks, contact-parameter sensitivity tests, and a comparison with literature data that places the simulation results in context. The machine-generated data are reproducible in principle and the sensitivity checks are a genuine strength. However, the central empirical claim—that β(AR) is S-shaped because of elongation—is undermined by a known confound with clump corrugation, and the microscopic explanation is explicitly acknowledged by the authors themselves to be incomplete. If the confound is resolved, the paper would make a solid contribution to the shape-dependent flow-rule literature.","major_comments":[{"comment":"The central claim that β(AR) is S-shaped due to elongation is confounded with clump corrugation. The convexity C_x (Eq. A1, Fig. 8b) drops from 0.971 at AR=1.3 to 0.917 at AR=1.5 and remains at 0.917 for AR≥1.5, while the sharp rise in β (Fig. 3d, Table II) occurs almost exactly over this same interval and both plateaus coincide with nearly constant C_x. The corrugation sensitivity test in Fig. 8(a) is performed only at AR=3 (C_x=0.917) and shows that increasing P_AR3 changes u/√gd substantially, so a corrugation of the magnitude present in the transition region is dynamically significant. The paper does not test whether the transition region AR=1.3–1.5 is sensitive to the number of spheres in the clump. The authors must either repeat the P_AR3 test at an intermediate AR (e.g., AR=1.4 or 1.5) with sufficient spheres per clump to keep C_x near unity, or use smooth particles (ellipsoids or superquadrics) in the transition region, to isolate elongation from discretization roughness. Without this, the reported S-shape may be an artifact of varying convexity rather than a genuine effect of aspect ratio.","section":"Appendix A, Fig. 8"},{"comment":"The paper overstates its microscopic explanation. The abstract and Section IV claim that the S-shape is understood (e.g., \"We understand this S-shaped dependence\" and the attribution of the first plateau to unchanged k_ω), but Section V explicitly states that \"neither particle alignment (S and αxz^p) nor rotation (k_ω) parameters exhibit a transition at AR ≈ 1.3 that is as sharp as in β.\" Since the sharp rise between AR=1.3 and 2.0 is the most distinctive feature of the S-shape, the proposed mechanistic account does not explain the phenomenon. The authors should revise the abstract and Section IV to present S, αxz^p, and k_ω as correlated trends that bracket the transition but do not reproduce its sharpness, or provide a new microscopic measure that captures that sharpness.","section":"Section V"},{"comment":"The logistic fit Eq. (4) has four free parameters (A_0, A_1, A_2, p) for only nine data points, and the transition region is constrained by just three points (AR=1.3, 1.4, 1.5). The sharpness parameter p=17.83 and the asymptotic values A_1 and A_2 are therefore not robust; a small change in one intermediate point would substantially shift the fitted transition. At minimum, the authors should fix A_1 and A_2 to the plateau averages (β≈0.23 and β≈0.53) and fit the remaining two parameters, report confidence intervals, and show sensitivity to excluding each of the three transition points. Alternatively, a piecewise fit with explicit plateau and transition domains would be more transparent than a four-parameter logistic.","section":"Eq. (4), Table II"}],"minor_comments":[{"comment":"In the text, \"a sharp transition similar to Fig. 3(c) is not observed\" should refer to Fig. 3(d), because Fig. 3(c) shows θ_1(AR) while Fig. 3(d) shows β(AR); as written, the reference is ambiguous.","section":"Section III.B"},{"comment":"Equation (7) extends the Pouliquen flow rule by inserting the fitted β_AR from Eq. (4), but the resulting friction law is never validated against an independent simulation (for example, an unsteady or non-uniform flow). A sentence clarifying that Eq. (7) is a proposed closure rather than a tested constitutive law would be appropriate.","section":"Eq. (7)"},{"comment":"The text says C_x \"remains unaltered for AR ≥ 1.5,\" but the reader must infer from the Fig. 8(b) caption that C_x is identical for AR=1.5, 2.0, 2.5, and 3.0 (all equal to 0.917). Stating this explicitly in the text would be clearer.","section":"Appendix A"},{"comment":"The order parameter S in Eq. (3) uses αxz^avg, the average orientation angle, which is not necessarily the nematic director for the skewed and broad distributions shown in Fig. 4(b). The definition should be clarified, or the standard nematic director (the eigenvector of the second-moment tensor) should be used to avoid ambiguity.","section":"Eq. (3)"},{"comment":"Table II reports large fitting errors for θ_2 (e.g., 60.99° ± 8.16° for AR=2.5), and the authors state that these errors do not affect their analysis. This should be justified explicitly, for example by showing that β is insensitive to plausible variations of θ_2 within its fitting uncertainty.","section":"Table II"}],"recommendation":"major_revision","confidential_remarks":"This is a carefully executed DEM study with useful sensitivity checks, but the corrugation confound in the transition region of AR is a genuine load-bearing issue that requires additional simulations. The authors' own concluding caveat further weakens the explanatory claims. If the confound can be removed or explicitly separated and the overstatements in the abstract and Section IV trimmed, the paper could be a solid contribution to shape-dependent flow-rule modeling. The scope of the journal is appropriate for this topic."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Read it. The genuinely new thing is the controlled AR scan from 1 to 3: beta, the slope of the Fr-h/hstop relation, is S-shaped in AR, flat below about 1.3 and above 2.0, with a sharp rise in between, and each AR does collapse onto its own Pouliquen line. That is a useful result. Earlier work had sphere and natural-grain endpoints; this fills the gap and gives a parametrization.\n\nThe paper earns credit for the work around the curve: steady-state DEM with per-AR collapse, error bars on beta that are small, sensitivity checks on stiffness, friction, restitution, domain size, and clump-sphere count, plus comparison against experimental glass-bead and irregular-particle data. The Appendix D check with the improved Pouliquen-Jenkins rule adds confidence. The conclusions are also honest, explicitly admitting that neither S, alpha_p^xz, nor k_omega shows the sharp transition that beta does.\n\nMain soft spot is the one flagged in the stress test, and it is real. The convexity Cx in Fig. 8(b) drops from 0.971 at AR=1.3 to 0.917 at AR=1.5, precisely across the sharp rise in beta, then stays constant through the upper plateau. Fig. 8(a) shows that smoother clumps at fixed AR=3 flow faster, so this corrugation-level roughness is dynamically relevant. The sensitivity test only runs in the plateau regime; it does not probe AR=1.3-1.5, where Cx changes most. That means the S-shape may be partly a clump-discretization effect rather than a pure elongation effect. This is not a minor caveat because the empirical beta-AR curve is the paper's central claim. To fix it, the authors need to vary the clump resolution (e.g., PAR3) at intermediate AR, or use smooth spherocylinders, and show the transition persists.\n\nSmaller issues: Eq. (4) is a four-parameter logistic fit to nine points, fine as a descriptor, but Eq. (7) adopts it as an extended basal friction law without independent validation. No code or data are provided, so reproduction is a re-implementation. The microscopic story stays correlational, as the authors say.\n\nBottom line: the paper is worth a serious referee. The beta-AR curve is plausible and useful, but I would not accept it until the corrugation confound in the transition region is addressed. I'd send it to review and ask for those simulations.","headline":"A useful AR-scan of Pouliquen's beta with a real S-curve, but the clumped-sphere corrugation confound in the transition region needs addressing before I'd trust the mechanistic story.","tokens_in":17500,"tokens_out":4353,"would_cite":true,"duration_ms":47168,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["45.70.Mg"],"model":"deepseek-v4-flash","headline":"This paper shows that the slope of Pouliquen's granular flow rule depends on particle aspect ratio in an S-shaped way, with plateaus for nearly spherical and strongly elongated grains, and packages this dependence into a shape-aware basal…","keywords":["granular flow","Pouliquen flow rule","particle aspect ratio","particle elongation","discrete element method","stopping thickness","basal friction","granular rheology"],"falsifier":"Perform additional DEM runs at finer $\\mathrm{AR}$ increments (about 1.25, 1.35, 1.45) using smoother clumps or true ellipsoids, and compute $k_\\omega$ from basal-layer angular velocities rather than layer averages; if $k_\\omega$ declines gradually instead of plateauing, or if the S-shape of $\\beta(\\mathrm{AR})$ shifts or disappears with better-resolved $\\mathrm{AR}$ or smoother particles, the proposed explanation and the general sigmoid fail.","tokens_in":16285,"feed_emoji":"🏔️","tokens_out":13930,"duration_ms":119362,"temperature":0.7,"pith_summary":"Granular flows in nature and industry involve non-spherical grains, yet particle-shape effects are usually left out of flow rules. The paper uses discrete-element simulations of clumped-sphere rods sliding down a rough incline, varying the length-to-diameter aspect ratio $\\mathrm{AR}$ from 1 to 3. It establishes that Pouliquen's scaling—Froude number proportional to $h/h_{\\text{stop}}$—works for every $\\mathrm{AR}$ separately, but the proportionality constant $\\beta$ is not universal: it stays near 0.22 for $\\mathrm{AR}\\le 1.3$, rises sharply to about 0.53 between $\\mathrm{AR}\\approx 1.3$ and 2, then plateaus. The authors capture this with a sigmoidal function of $\\mathrm{AR}$ and use it to derive a basal-friction law for shallow avalanche models that depends on flow thickness, Froude number, and aspect ratio. The micromechanical explanation attributes the first plateau to unchanged rotation ability and the second to saturation of orientation, while the paper itself notes that neither microscopic quantity transitions as sharply as $\\beta$.","feed_headline":"Grain shape bends the granular flow rule into an S-curve","feed_subtitle":"Above aspect ratio ~1.3 the mobility slope jumps, then saturates; a logistic fit yields a shape-aware friction law.","key_machinery":"Pouliquen's flow rule is the skeleton: flows down a rough incline are characterized by the stopping thickness $h_{\\text{stop}}(\\theta)$ and the collapse of the Froude number $Fr = u/\\sqrt{gh}$ against $h/h_{\\text{stop}}$ onto a straight line $Fr = \\beta\\, h/h_{\\text{stop}}$. The $h_{\\text{stop}}$ curve is fit by $h_{\\text{stop}}/d = A(\\tan\\theta_2 - \\tan\\theta)/(\\tan\\theta - \\tan\\theta_1)$, which yields the dynamic angle of repose $\\theta_1$. The shape dependence enters through the fitted slope $\\beta$, modelled by the logistic function of Eq. (4). To interpret the S-shape, the paper uses the orientation order parameter $S = (3\\langle\\cos^2(\\alpha_{xz} - \\alpha_{xz}^{\\text{avg}})\\rangle - 1)/2$, the preferred side-view orientation angle $\\alpha_{xz}^p$, and the rotation ability $k_\\omega$, the slope of layer-averaged angular velocity $\\omega$ versus shear rate $\\dot{\\gamma}$. The argument is that $k_\\omega$'s plateau for $\\mathrm{AR}\\lesssim 1.3$ explains the first plateau in $\\beta$, while the saturation of alignment and orientation beyond $\\mathrm{AR}\\approx 2$ explains the second; Eq. (4) then lifts $\\beta$ into a basal friction law for shallow-flow equations.","core_discovery":"The central claim is that grain elongation enters Pouliquen's flow rule through a single shape-dependent coefficient. For each aspect ratio tested, all steady flows collapse onto a line $Fr = \\beta\\, h/h_{\\text{stop}}$, but $\\beta$ depends on $\\mathrm{AR}$ in three regimes: a low plateau ($\\beta \\approx 0.22$–0.24) for $\\mathrm{AR}\\lesssim 1.3$, a sharp rise to $\\beta\\approx 0.53$ for $1.3\\lesssim\\mathrm{AR}\\lesssim 2$, and a high plateau beyond $\\mathrm{AR}\\approx 2$. Fitting $\\beta(\\mathrm{AR})$ with the logistic form $\\beta_{\\mathrm{AR}} = A_2 + (A_1 - A_2)/(1 + (\\mathrm{AR}/A_0)^p)$ with $A_0\\approx 1.46$, $A_1\\approx 0.22$, $A_2\\approx 0.53$, $p\\approx 17.8$, and combining it with the $h_{\\text{stop}}$ fit gives an extended Pouliquen friction law $\\mu_b(h, Fr, \\mathrm{AR})$. At the particle scale, the paper attributes the low-AR plateau to an essentially unchanged rotation ability $k_\\omega$ (the slope of angular velocity versus shear rate) for weakly elongated grains, and the high-AR plateau to saturation of particle alignment and preferred orientation. The authors state that neither $k_\\omega$ nor the orientation order parameter $S$ changes as sharply at $\\mathrm{AR}\\approx 1.3$ as $\\beta$ does, so the sharp transition is empirically robust but lacks a single sharp microscopic order parameter.","pith_inferences":["If the S-shape is generic, natural samples with a broad distribution of grain aspect ratios should smear the transition; an effective $\\beta$ for a polydisperse mixture may be a weighted average over $\\mathrm{AR}$, which could be tested with binary-AR DEM mixtures.","The corrugation sensitivity in the paper's Appendix A suggests that the sharp rise near $\\mathrm{AR}\\approx 1.4$–1.5 may partly reflect the roughness of clumped-sphere particles, not aspect ratio alone; repeating the sweep with ellipsoids or smoother clumps could shift the transition.","The plateau of $k_\\omega$ near 0.5, and its possible link to the vorticity-to-shear-rate ratio in fluids, hints that weakly elongated grains might be treated as rotationally spherical in continuum models, with shape entering only through modified contact-level friction—an extension the paper does not make.","Because $\\beta$ sets depth-averaged speed in avalanche equations, the $\\mathrm{AR}$-dependent friction law could be coupled to segregation or erosion models for non-spherical grains, connecting single-flow mobility to deposit patterns."],"forward_implications":["For monodisperse elongated grains, Pouliquen's collapse still holds within each aspect ratio, so depth-averaged models can be extended by letting $\\beta$ depend on $\\mathrm{AR}$.","Particle elongation makes flows harder to mobilize—$h_{\\text{stop}}$ shifts to larger angles and thicknesses—but this effect saturates around $\\mathrm{AR}\\approx 2$, after which further elongation changes mobility little.","The logistic $\\beta(\\mathrm{AR})$ relation, combined with the $h_{\\text{stop}}$ fit, gives an explicit basal friction law $\\mu_b(h, Fr, \\mathrm{AR})$ that can be inserted into the mass- and momentum-conservation equations used for shallow granular avalanches.","Weakly elongated grains ($\\mathrm{AR}\\lesssim 1.3$) rotate essentially like spheres, so shape effects in this regime must act through alignment and geometry rather than through rotation.","Because neither $k_\\omega$ nor $S$ transitions as sharply as $\\beta$, a single microscopic order parameter for the sphere-to-rod crossover remains missing; finding it is a concrete next step."],"supporting_citations":[{"why":"supplies the $h_{\\text{stop}}$ curve and the $Fr$-$h/h_{\\text{stop}}$ scaling framework that the paper extends to elongated particles.","marker":"[17]"},{"why":"shows that sand (irregularly shaped grains) obeys the scaling with a steeper slope, motivating a shape-dependent $\\beta$, and anchors the shallow-flow equations.","marker":"[1]"},{"why":"provides experimental data for glass beads, sand, and copper particles that form the low-AR and high-AR clusters bridged by the S-shaped transition.","marker":"[18]"},{"why":"sets the DEM protocol for thin and thick flows on a rough incline and supplies spherical-particle reference data.","marker":"[26]"},{"why":"adds DEM results for frictional shallow granular flows and gives further spherical $\\beta$ values for comparison.","marker":"[25]"},{"why":"introduces the rotation-ability measure $k_\\omega$ and its plateau near 0.5 used to explain the low-AR plateau.","marker":"[12]"},{"why":"documents the clumped-sphere corrugation effect and preferential alignment of rod-like particles, guiding the particle model and orientation analysis.","marker":"[20]"},{"why":"supplies the baseline DEM contact model and bottom-roughness setup for inclined-plane granular flow.","marker":"[22]"},{"why":"describes the linear spring-dashpot contact model whose normal and tangential forces are used in the simulations.","marker":"[11]"}],"fun_headline_variants":["Grain elongation bends granular flow rule into S-curve","Aspect ratio shapes granular flow: S-shaped slope transition","Grain shape flips mobility slope after aspect ratio ~1.3","Elongated grains: flow rule gains S-shaped shape dependence","Aspect ratio enters granular friction law via sigmoid"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is that the layer-averaged rotation ability $k_\\omega$ faithfully measures how particle elongation restricts rotation, and that its flat behavior for $\\mathrm{AR}\\lesssim 1.3$ is what produces the first plateau in $\\beta$; the paper itself concedes that neither $k_\\omega$ nor the orientation order parameter transitions as sharply as $\\beta$, so if $k_\\omega$ is sensitive to layer averaging or to the coarse $\\mathrm{AR}$ sampling, the mechanistic explanation would need revision.","fun_headline_variants_meta":{"raw":{"variants":["Grain elongation bends granular flow rule into S-curve","Aspect ratio shapes granular flow: S-shaped slope transition","Grain shape flips mobility slope after aspect ratio ~1.3","Elongated grains: flow rule gains S-shaped shape dependence","Aspect ratio enters granular friction law via sigmoid"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00058,"raw_usage":{"total_tokens":2869,"prompt_tokens":1220,"completion_tokens":1649,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":836,"completion_tokens_details":{"reasoning_tokens":1565}},"tokens_in":836,"tokens_out":1649,"duration_ms":13315,"temperature":1.0,"reasoning_tokens":1565,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-10T19:02:01.392714+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Perform additional DEM runs at finer $\\mathrm{AR}$ increments (about 1.25, 1.35, 1.45) using smoother clumps or true ellipsoids, and compute $k_\\omega$ from basal-layer angular velocities rather than layer averages; if $k_\\omega$ declines gradually instead of plateauing, or if the S-shape of $\\beta(\\mathrm{AR})$ shifts or disappears with better-resolved $\\mathrm{AR}$ or smoother particles, the proposed explanation and the general sigmoid fail.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"supplies the $h_{\\text{stop}}$ curve and the $Fr$-$h/h_{\\text{stop}}$ scaling framework that the paper extends to elongated particles."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"shows that sand (irregularly shaped grains) obeys the scaling with a steeper slope, motivating a shape-dependent $\\beta$, and anchors the shallow-flow equations."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"provides experimental data for glass beads, sand, and copper particles that form the low-AR and high-AR clusters bridged by the S-shaped transition."},{"cited_title":"[25] for simulations","cited_arxiv_id":null,"evidence_quote":"sets the DEM protocol for thin and thick flows on a rough incline and supplies spherical-particle reference data."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"adds DEM results for frictional shallow granular flows and gives further spherical $\\beta$ values for comparison."},{"cited_title":"Mandal and D","cited_arxiv_id":null,"evidence_quote":"introduces the rotation-ability measure $k_\\omega$ and its plateau near 0.5 used to explain the low-AR plateau."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"documents the clumped-sphere corrugation effect and preferential alignment of rod-like particles, guiding the particle model and orientation analysis."},{"cited_title":"B¨ orzs¨ onyi and R","cited_arxiv_id":null,"evidence_quote":"supplies the baseline DEM contact model and bottom-roughness setup for inclined-plane granular flow."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"describes the linear spring-dashpot contact model whose normal and tangential forces are used in the simulations."}],"review_version":1}